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  • MySQLi - declaring variable after bind_param?

    - by Kerry
    This may be a completely dumb question, but I've seen a couple examples declaring the variables AFTER putting them in bind_param: http://devzone.zend.com/article/686 I've never seen this done before and all my programming knowledge says I should define them before hand. Is this a valid/preferred way?

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  • Is there a (Linux) C++ IDE that can 'construct' a project from a makefile?

    - by Paul
    I am working on a legacy C app which uses makefiles. I am more comfortable (and more productive) working from within an IDE, so I am looking for an IDE that can import the makefile and create a project. Incidentally, these are hand written makefiles (not complicated ones like those generated by Autoconf). I am using Code::Blocks at the moment, but it seems it is unable to import makefiles ...

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  • finding elements with text using jQuery

    - by Tim Sheiner
    I want to create an array of all the html elements within a div that contain text strings, such as <p>some string</p>. I don't want to get hold of the strings, I want the array items to be the elements (in the example, would be the p node). I do not know before hand what the strings will be, so I can't look for string values to match. I also don't want empty text nodes to end up in the array. Thanks!

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  • How to calculate the cycles that change one permutation into another?

    - by fortran
    Hi, I'm looking for an algorithm that given two permutations of a sequence (e.g. [2, 3, 1, 4] and [4, 1, 3, 2]) calculates the cycles that are needed to convert the first into the second (for the example, [[0, 3], [1, 2]]). The link from mathworld says that Mathematica's ToCycle function does that, but sadly I don't have any Mathematica license at hand... I'd gladly receive any pointer to an implementation of the algorithm in any FOSS language or mathematics package. Thanks!

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  • C# Creating A Program That Runs In The Background?

    - by Soo
    How can I create a program that runs in the background, and can be accessed via the Windows' "Notification Area" (Where the date and time are in the lower right hand corner)? In other words, I want to be able to create a program that runs and can toggle between having a display window and not having a display window.

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  • UIWebView from Navigation Bar button

    - by Dixit
    Im having issue with button on a top right hand side of naviogation bar on iOS: I have a button that can launch a app.html file from app itself and show on top of current view and That popup webview can be minimize with dDone button on it, Im having issues doing this, How can i call UIWebView on top of current view and allow it to launch app.html page from app directory. Currently i have: - (BOOL)webView:(UIWebView *)webViewer shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType{ } and this is a button that call that function UIBarButtonItem *showAppMenu = [[UIBarButtonItem alloc] initWithTitle:@"Help" style:UIBarButtonItemStylePlain target:self action:@selector(webView)];

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  • Is it possible to integrate Google Maps with the directions and the Transit layer into an iPhone app

    - by t4v
    Sorry if this question is obvious for some of you. I know we can link to the existing Goggle Maps app, but I would like to have an app that does not exit and provides the direction within. I intend using GTFS for public transit. On the other hand, would it be possible to plot a line inside the iPhone app the results as returned by Google Transit? (say, I send it the arrival and departure addresses) Thank you so much!

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  • C/C++ variable length automatic array performance

    - by aaa
    hello. Is there significant cpu/memory overhead associated with using automatic arrays with g++/Intel on 64-bit x86 linux platform? int function(int N) { double array[N]; overhead compared to allocating array before hand (assuming function is called multiple times) overhead compared to using new overhead compared to using malloc range of N maybe from 1kb to 16kb roughly, stack overrun is not a problem Thank you

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  • How can I limit the number of registrants to an event?

    - by user356900
    I've set up a basic html/php submission form where people can register for our event, but need a way to replace the submission form webpage with one that reads something like "We have reached our registration limit" when we reach a certain number of submitted forms. Our database is MySQL (if that makes a difference) I've looked around on the web but people either say to count the entries by hand, or the ones that do have an automated system use CMS like drupal or joomla. Is it possible to setup an automated script that will do this?

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  • Cannot turn on "Network Discovery and File Sharing" when Windows Firewall is enabled

    - by Cheeso
    I have a problem similar to this one. Windows Firewall prevents File and Printer sharing from working and Why does File and Printer Sharing keep turning off in Windows 7? I cannot turn on Network Discovery. This is Windows 7 Home Premium, x64. It's a Dell XPS 1340 and Windows came installed from the OEM. This used to work. Now it doesn't. I don't know what has changed. In windows Explorer, the UI looks like this: When I click the yellow panel that says "Click to change...", the panel disappears, then immediately reappears, with exactly the same text. If I go through the control panel "Network and Sharing Center" thing, the UI looks like this: If I tick the box to "turn on network discovery", the "Save Changes" button becomes enabled. If I then click that button, the dialog box just closes, with no message or confirmation. Re-opening the same dialog box shows that Network Discovery has not been turned on. If I turn off Windows Firewall, I can then turn on Network Discovery via either method. The machine is connected to a wireless home network, via a router. The network is marked as "Home Network" in the Network and Sharing Center, which I think corresponds to the "Private" profile in Windows Firewall Advanced Settings app. (Confirm?) The PC is not part of a domain, and has never been part of a domain. The machine is not bridging any networks. There is a regular 100baseT connector but I have the network adapter for that disabled in Windows. Something else that seems odd. Within Windows Firewall Advanced Settings, there are no predefined rules available. If I click the "New Rule...." Action on the action pane, the "Predefined" option is greyed out. like this: In order to attempt to allow the network discovery protocols through on the private network, I hand-coded a bunch of rules, intending to allow the necessary UPnP and WDP protocols supporting network discovery. I copied them from a working Windows 7 Ultimate PC, running on the same network. This did not work. Even with the hand-coded rules, I still cannot turn on Network Discovery. I looked on the interwebs, and the only solution that appears to work is a re-install of Windows. Seriously? If I try netsh advfirewall firewall set rule group="Network Discovery" new enable=Yes ...it says "No rules match the specified criteria" EDIT: by the way, these services are running. DNS Client Function Discovery Resource Publication SSDP Discovery UPnP Device Host in any case, since it works with no firewall, I would assume all necessary services are present and running. The issue is a firewall thing, but I don't know how to diagnose further, or fix it. Q1: Is there a way to definitively insure the correct holes are punched through the Windows Firewall to allow Network Discovery to function? Q2: Should I expect the "predefined" firewall rules to be greyed out? Q3: Why did this change?

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  • How to configure emacs by using this file?

    - by Andy Leman
    From http://public.halogen-dg.com/browser/alex-emacs-settings/.emacs?rev=1346 I got: (setq load-path (cons "/home/alex/.emacs.d/" load-path)) (setq load-path (cons "/home/alex/.emacs.d/configs/" load-path)) (defconst emacs-config-dir "~/.emacs.d/configs/" "") (defun load-cfg-files (filelist) (dolist (file filelist) (load (expand-file-name (concat emacs-config-dir file))) (message "Loaded config file:%s" file) )) (load-cfg-files '("cfg_initsplit" "cfg_variables_and_faces" "cfg_keybindings" "cfg_site_gentoo" "cfg_conf-mode" "cfg_mail-mode" "cfg_region_hooks" "cfg_apache-mode" "cfg_crontab-mode" "cfg_gnuserv" "cfg_subversion" "cfg_css-mode" "cfg_php-mode" "cfg_tramp" "cfg_killbuffer" "cfg_color-theme" "cfg_uniquify" "cfg_tabbar" "cfg_python" "cfg_ack" "cfg_scpaste" "cfg_ido-mode" "cfg_javascript" "cfg_ange_ftp" "cfg_font-lock" "cfg_default_face" "cfg_ecb" "cfg_browser" "cfg_orgmode" ; "cfg_gnus" ; "cfg_cyrillic" )) ; enable disabled advanced features (put 'downcase-region 'disabled nil) (put 'scroll-left 'disabled nil) (put 'upcase-region 'disabled nil) ; narrow cursor ;(setq-default cursor-type 'hbar) (cua-mode) ; highlight current line (global-hl-line-mode 1) ; AV: non-aggressive scrolling (setq scroll-conservatively 100) (setq scroll-preserve-screen-position 't) (setq scroll-margin 0) (custom-set-variables ;; custom-set-variables was added by Custom. ;; If you edit it by hand, you could mess it up, so be careful. ;; Your init file should contain only one such instance. ;; If there is more than one, they won't work right. '(ange-ftp-passive-host-alist (quote (("redbus2.chalkface.com" . "on") ("zope.halogen-dg.com" . "on") ("85.119.217.50" . "on")))) '(blink-cursor-mode nil) '(browse-url-browser-function (quote browse-url-firefox)) '(browse-url-new-window-flag t) '(buffers-menu-max-size 30) '(buffers-menu-show-directories t) '(buffers-menu-show-status nil) '(case-fold-search t) '(column-number-mode t) '(cua-enable-cua-keys nil) '(user-mail-address "[email protected]") '(cua-mode t nil (cua-base)) '(current-language-environment "UTF-8") '(file-name-shadow-mode t) '(fill-column 79) '(grep-command "grep --color=never -nHr -e * | grep -v .svn --color=never") '(grep-use-null-device nil) '(inhibit-startup-screen t) '(initial-frame-alist (quote ((width . 80) (height . 40)))) '(initsplit-customizations-alist (quote (("tabbar" "configs/cfg_tabbar.el" t) ("ecb" "configs/cfg_ecb.el" t) ("ange\\-ftp" "configs/cfg_ange_ftp.el" t) ("planner" "configs/cfg_planner.el" t) ("dired" "configs/cfg_dired.el" t) ("font\\-lock" "configs/cfg_font-lock.el" t) ("speedbar" "configs/cfg_ecb.el" t) ("muse" "configs/cfg_muse.el" t) ("tramp" "configs/cfg_tramp.el" t) ("uniquify" "configs/cfg_uniquify.el" t) ("default" "configs/cfg_font-lock.el" t) ("ido" "configs/cfg_ido-mode.el" t) ("org" "configs/cfg_orgmode.el" t) ("gnus" "configs/cfg_gnus.el" t) ("nnmail" "configs/cfg_gnus.el" t)))) '(ispell-program-name "aspell") '(jabber-account-list (quote (("[email protected]")))) '(jabber-nickname "AVK") '(jabber-password nil) '(jabber-server "halogen-dg.com") '(jabber-username "alex") '(remember-data-file "~/Plans/remember.org") '(safe-local-variable-values (quote ((dtml-top-element . "body")))) '(save-place t nil (saveplace)) '(scroll-bar-mode (quote right)) '(semantic-idle-scheduler-idle-time 432000) '(show-paren-mode t) '(svn-status-hide-unmodified t) '(tool-bar-mode nil nil (tool-bar)) '(transient-mark-mode t) '(truncate-lines f) '(woman-use-own-frame nil)) ; ?? ????? ??????? y ??? n? (fset 'yes-or-no-p 'y-or-n-p) (custom-set-faces ;; custom-set-faces was added by Custom. ;; If you edit it by hand, you could mess it up, so be careful. ;; Your init file should contain only one such instance. ;; If there is more than one, they won't work right. '(compilation-error ((t (:foreground "tomato" :weight bold)))) '(cursor ((t (:background "red1")))) '(custom-variable-tag ((((class color) (background dark)) (:inherit variable-pitch :foreground "DarkOrange" :weight bold)))) '(hl-line ((t (:background "grey24")))) '(isearch ((t (:background "orange" :foreground "black")))) '(message-cited-text ((((class color) (background dark)) (:foreground "SandyBrown")))) '(message-header-name ((((class color) (background dark)) (:foreground "DarkGrey")))) '(message-header-other ((((class color) (background dark)) (:foreground "LightPink2")))) '(message-header-subject ((((class color) (background dark)) (:foreground "yellow2")))) '(message-separator ((((class color) (background dark)) (:foreground "thistle")))) '(region ((t (:background "brown")))) '(tooltip ((((class color)) (:inherit variable-pitch :background "IndianRed1" :foreground "black"))))) The above is a python emacs configure file. Where should I put it to use it? And, are there any other changes I need to make?

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  • Random Slow Response

    - by ARehman
    We have an ASP.NET MVC 1.0 application running on Windows Server 2008 – Standard (32 –bit), Dual Core Xeon (3.0 GHz), 2 G.B R.A.M. Most of the times application renders response in 3-4 seconds, but sometimes users get very late response and delay is up to 40 seconds or more than a minute. It happens in following way: User browsed a page, idle for 5, 10 or 15 minutes, tried to browse same page or some other. Now, there is a chance that he will see late response whereas the app pool is still up and running. This can happen with any arbitrary page. We have tried followings/observations. Moved the application to stand alone web server App Pool idle shutdown time is 60 minutes. There are no abrupt shut downs/restarts. CPU or memory doesn’t spike. No delays in SQL queries. Modified App Pool setting to run in classic-mode. It didn’t help. Plugged-in custom module to log all those requests which took more than 5 seconds to complete. It didn’t pick any request of interest. Enabled ‘Failed Request Tracing’ to log all those requests which take 20 or more seconds to complete. It didn’t log anything. Event Viewer, HTTPER log, W3SVC logs or WAS logs don’t indicate anything. HTTPERR only has ‘_ _ Timer_ConnectionIdle _ _’ entries. There is not much traffic to server. This can happen also if only two users are active. Next we captured TCP/IP terrific on both a user and server end with Wireshark and below are details in brief of this slowness: Browser sends a request for ~/User/Home/ (GET Request) by setting up a receiving end point using port 'wlbs(port-2504)'. I'm not sure if this could be a problem in some way that browser didn't hand-shake with the server first and assumed that last connection is still open, whereas, I browsed the same page 4 minutes ago and didn't perform any activity with site after that. If I see the HTTPERR log, it indicates that it has ‘_ _ Timer_ConnectionIdle _ _ _’ entry for my last activity with server. Browser (I was using Chrome) waits for any response from the server, doesn’t find any then starts retransmitting the same request using same end point after incrementing wait intervals, e.g. after 8, 18, 29, 40, 62, and 92 seconds. All these GET requests were received by server as well. But, server didn’t send any packet to client. Browser didn't see any response on the end point it set up in point 1, it opened a new end point 'optiwave-lm (port-2524)', did a hand shake with the server and transmitted the same request again. Server received, processed it, and returned successful response. What happened to earlier 6-7 requests? Whether they were passed on to HTTP.SYS or not? Why Failed Request Tracing not logged anything, we didn't find any clue yet. Server served the same page successfully just 4 minutes ago. Looking forward for more suggestions/solutions. -- Thanks

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  • Configuring a PIX 506e for Asterisk

    - by orthogonal3
    Hi all! I'm having problems configuring a old Cisco PIX running 6.3 and wondered if anyone can lend a hand? Simply put I have a PIX 506e that I want to put in my VoIP data path. I can't update it and getting a compat version of Java for that version of PIX is tough so I can't log onto the web interface. The PIX straddles two networks..... 192.168.5.0 on the inside, ...50.0 on the outside both net masks are 255.255.255.0 I have a local Asterisk server cluster with a single service IP (<local asterisk>) SIP is on UDP 5060 and RTP (for the voip data) is on UDP 18000-18999 I know thats a big range but hey may as well. I need the 192.168.5.0 net to have web and ftp access for updates and the like. DHCP, DNS and NTP is already provided on that network so I don't need external DNS access. So I think I want the following rules: SIP or RTP from <my itsp> arriving at <outside voip ip> NATed to <local asterisk> SIP or RTP able to do the reverse route (should be covered by high sec - low sec??) HTTP and FTP access outbound for software update for the servers etc I have the following config at the minute - and I think I'm almost there (I hope)... interface ethernet0 auto interface ethernet1 auto nameif ethernet0 outside security0 nameif ethernet1 inside security100 enable password wouldyouliketobeapeppertoo encrypted passwd wouldyouliketobeapeppertoo encrypted hostname afirewall domain-name adomain fixup protocol dns maximum-length 512 fixup protocol ftp 21 fixup protocol h323 h225 1720 fixup protocol h323 ras 1718-1719 fixup protocol http 80 fixup protocol rsh 514 fixup protocol rtsp 554 fixup protocol sip 5060 fixup protocol sip udp 5060 fixup protocol skinny 2000 fixup protocol smtp 25 fixup protocol sqlnet 1521 fixup protocol tftp 69 access-list acl_ping permit icmp any any access-list voip permit ip host <my itsp> host <local asterisk> mtu outside 1500 mtu inside 1500 ip address outside <outside pix ip> 255.255.255.0 ip address inside <inside pix ip> 255.255.255.0 arp timeout 14400 global (outside) 1 <outside generic ip> nat (inside) 1 192.168.5.0 255.255.255.0 0 0 static (inside,outside) <outside voip ip> <local asterisk> netmask 255.255.255.255 0 0 static (outside,inside) <local asterisk> <outside voip ip> netmask 255.255.255.255 0 0 access-group acl_ping in interface outside access-group acl_ping in interface inside route outside 0.0.0.0 0.0.0.0 <my next hop router> 1 route outside <my itsp> 255.255.255.255 <my next hop router> 1 I think I just need a hand with the access-lists and NAT/static rules. Would anyone be able to help as I've RTFM'd the Cisco docs a few times and they're heavy. Wishing I'd completed my CCNA now! Thanks all for any help, Phil

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  • value types in the vm

    - by john.rose
    value types in the vm p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} p.p2 {margin: 0.0px 0.0px 14.0px 0.0px; font: 14.0px Times} p.p3 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times} p.p4 {margin: 0.0px 0.0px 15.0px 0.0px; font: 14.0px Times} p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier} p.p6 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier; min-height: 17.0px} p.p7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p8 {margin: 0.0px 0.0px 0.0px 36.0px; text-indent: -36.0px; font: 14.0px Times; min-height: 18.0px} p.p9 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p10 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; color: #000000} li.li1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} li.li7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} span.s1 {font: 14.0px Courier} span.s2 {color: #000000} span.s3 {font: 14.0px Courier; color: #000000} ol.ol1 {list-style-type: decimal} Or, enduring values for a changing world. Introduction A value type is a data type which, generally speaking, is designed for being passed by value in and out of methods, and stored by value in data structures. The only value types which the Java language directly supports are the eight primitive types. Java indirectly and approximately supports value types, if they are implemented in terms of classes. For example, both Integer and String may be viewed as value types, especially if their usage is restricted to avoid operations appropriate to Object. In this note, we propose a definition of value types in terms of a design pattern for Java classes, accompanied by a set of usage restrictions. We also sketch the relation of such value types to tuple types (which are a JVM-level notion), and point out JVM optimizations that can apply to value types. This note is a thought experiment to extend the JVM’s performance model in support of value types. The demonstration has two phases.  Initially the extension can simply use design patterns, within the current bytecode architecture, and in today’s Java language. But if the performance model is to be realized in practice, it will probably require new JVM bytecode features, changes to the Java language, or both.  We will look at a few possibilities for these new features. An Axiom of Value In the context of the JVM, a value type is a data type equipped with construction, assignment, and equality operations, and a set of typed components, such that, whenever two variables of the value type produce equal corresponding values for their components, the values of the two variables cannot be distinguished by any JVM operation. Here are some corollaries: A value type is immutable, since otherwise a copy could be constructed and the original could be modified in one of its components, allowing the copies to be distinguished. Changing the component of a value type requires construction of a new value. The equals and hashCode operations are strictly component-wise. If a value type is represented by a JVM reference, that reference cannot be successfully synchronized on, and cannot be usefully compared for reference equality. A value type can be viewed in terms of what it doesn’t do. We can say that a value type omits all value-unsafe operations, which could violate the constraints on value types.  These operations, which are ordinarily allowed for Java object types, are pointer equality comparison (the acmp instruction), synchronization (the monitor instructions), all the wait and notify methods of class Object, and non-trivial finalize methods. The clone method is also value-unsafe, although for value types it could be treated as the identity function. Finally, and most importantly, any side effect on an object (however visible) also counts as an value-unsafe operation. A value type may have methods, but such methods must not change the components of the value. It is reasonable and useful to define methods like toString, equals, and hashCode on value types, and also methods which are specifically valuable to users of the value type. Representations of Value Value types have two natural representations in the JVM, unboxed and boxed. An unboxed value consists of the components, as simple variables. For example, the complex number x=(1+2i), in rectangular coordinate form, may be represented in unboxed form by the following pair of variables: /*Complex x = Complex.valueOf(1.0, 2.0):*/ double x_re = 1.0, x_im = 2.0; These variables might be locals, parameters, or fields. Their association as components of a single value is not defined to the JVM. Here is a sample computation which computes the norm of the difference between two complex numbers: double distance(/*Complex x:*/ double x_re, double x_im,         /*Complex y:*/ double y_re, double y_im) {     /*Complex z = x.minus(y):*/     double z_re = x_re - y_re, z_im = x_im - y_im;     /*return z.abs():*/     return Math.sqrt(z_re*z_re + z_im*z_im); } A boxed representation groups component values under a single object reference. The reference is to a ‘wrapper class’ that carries the component values in its fields. (A primitive type can naturally be equated with a trivial value type with just one component of that type. In that view, the wrapper class Integer can serve as a boxed representation of value type int.) The unboxed representation of complex numbers is practical for many uses, but it fails to cover several major use cases: return values, array elements, and generic APIs. The two components of a complex number cannot be directly returned from a Java function, since Java does not support multiple return values. The same story applies to array elements: Java has no ’array of structs’ feature. (Double-length arrays are a possible workaround for complex numbers, but not for value types with heterogeneous components.) By generic APIs I mean both those which use generic types, like Arrays.asList and those which have special case support for primitive types, like String.valueOf and PrintStream.println. Those APIs do not support unboxed values, and offer some problems to boxed values. Any ’real’ JVM type should have a story for returns, arrays, and API interoperability. The basic problem here is that value types fall between primitive types and object types. Value types are clearly more complex than primitive types, and object types are slightly too complicated. Objects are a little bit dangerous to use as value carriers, since object references can be compared for pointer equality, and can be synchronized on. Also, as many Java programmers have observed, there is often a performance cost to using wrapper objects, even on modern JVMs. Even so, wrapper classes are a good starting point for talking about value types. If there were a set of structural rules and restrictions which would prevent value-unsafe operations on value types, wrapper classes would provide a good notation for defining value types. This note attempts to define such rules and restrictions. Let’s Start Coding Now it is time to look at some real code. Here is a definition, written in Java, of a complex number value type. @ValueSafe public final class Complex implements java.io.Serializable {     // immutable component structure:     public final double re, im;     private Complex(double re, double im) {         this.re = re; this.im = im;     }     // interoperability methods:     public String toString() { return "Complex("+re+","+im+")"; }     public List<Double> asList() { return Arrays.asList(re, im); }     public boolean equals(Complex c) {         return re == c.re && im == c.im;     }     public boolean equals(@ValueSafe Object x) {         return x instanceof Complex && equals((Complex) x);     }     public int hashCode() {         return 31*Double.valueOf(re).hashCode()                 + Double.valueOf(im).hashCode();     }     // factory methods:     public static Complex valueOf(double re, double im) {         return new Complex(re, im);     }     public Complex changeRe(double re2) { return valueOf(re2, im); }     public Complex changeIm(double im2) { return valueOf(re, im2); }     public static Complex cast(@ValueSafe Object x) {         return x == null ? ZERO : (Complex) x;     }     // utility methods and constants:     public Complex plus(Complex c)  { return new Complex(re+c.re, im+c.im); }     public Complex minus(Complex c) { return new Complex(re-c.re, im-c.im); }     public double abs() { return Math.sqrt(re*re + im*im); }     public static final Complex PI = valueOf(Math.PI, 0.0);     public static final Complex ZERO = valueOf(0.0, 0.0); } This is not a minimal definition, because it includes some utility methods and other optional parts.  The essential elements are as follows: The class is marked as a value type with an annotation. The class is final, because it does not make sense to create subclasses of value types. The fields of the class are all non-private and final.  (I.e., the type is immutable and structurally transparent.) From the supertype Object, all public non-final methods are overridden. The constructor is private. Beyond these bare essentials, we can observe the following features in this example, which are likely to be typical of all value types: One or more factory methods are responsible for value creation, including a component-wise valueOf method. There are utility methods for complex arithmetic and instance creation, such as plus and changeIm. There are static utility constants, such as PI. The type is serializable, using the default mechanisms. There are methods for converting to and from dynamically typed references, such as asList and cast. The Rules In order to use value types properly, the programmer must avoid value-unsafe operations.  A helpful Java compiler should issue errors (or at least warnings) for code which provably applies value-unsafe operations, and should issue warnings for code which might be correct but does not provably avoid value-unsafe operations.  No such compilers exist today, but to simplify our account here, we will pretend that they do exist. A value-safe type is any class, interface, or type parameter marked with the @ValueSafe annotation, or any subtype of a value-safe type.  If a value-safe class is marked final, it is in fact a value type.  All other value-safe classes must be abstract.  The non-static fields of a value class must be non-public and final, and all its constructors must be private. Under the above rules, a standard interface could be helpful to define value types like Complex.  Here is an example: @ValueSafe public interface ValueType extends java.io.Serializable {     // All methods listed here must get redefined.     // Definitions must be value-safe, which means     // they may depend on component values only.     List<? extends Object> asList();     int hashCode();     boolean equals(@ValueSafe Object c);     String toString(); } //@ValueSafe inherited from supertype: public final class Complex implements ValueType { … The main advantage of such a conventional interface is that (unlike an annotation) it is reified in the runtime type system.  It could appear as an element type or parameter bound, for facilities which are designed to work on value types only.  More broadly, it might assist the JVM to perform dynamic enforcement of the rules for value types. Besides types, the annotation @ValueSafe can mark fields, parameters, local variables, and methods.  (This is redundant when the type is also value-safe, but may be useful when the type is Object or another supertype of a value type.)  Working forward from these annotations, an expression E is defined as value-safe if it satisfies one or more of the following: The type of E is a value-safe type. E names a field, parameter, or local variable whose declaration is marked @ValueSafe. E is a call to a method whose declaration is marked @ValueSafe. E is an assignment to a value-safe variable, field reference, or array reference. E is a cast to a value-safe type from a value-safe expression. E is a conditional expression E0 ? E1 : E2, and both E1 and E2 are value-safe. Assignments to value-safe expressions and initializations of value-safe names must take their values from value-safe expressions. A value-safe expression may not be the subject of a value-unsafe operation.  In particular, it cannot be synchronized on, nor can it be compared with the “==” operator, not even with a null or with another value-safe type. In a program where all of these rules are followed, no value-type value will be subject to a value-unsafe operation.  Thus, the prime axiom of value types will be satisfied, that no two value type will be distinguishable as long as their component values are equal. More Code To illustrate these rules, here are some usage examples for Complex: Complex pi = Complex.valueOf(Math.PI, 0); Complex zero = pi.changeRe(0);  //zero = pi; zero.re = 0; ValueType vtype = pi; @SuppressWarnings("value-unsafe")   Object obj = pi; @ValueSafe Object obj2 = pi; obj2 = new Object();  // ok List<Complex> clist = new ArrayList<Complex>(); clist.add(pi);  // (ok assuming List.add param is @ValueSafe) List<ValueType> vlist = new ArrayList<ValueType>(); vlist.add(pi);  // (ok) List<Object> olist = new ArrayList<Object>(); olist.add(pi);  // warning: "value-unsafe" boolean z = pi.equals(zero); boolean z1 = (pi == zero);  // error: reference comparison on value type boolean z2 = (pi == null);  // error: reference comparison on value type boolean z3 = (pi == obj2);  // error: reference comparison on value type synchronized (pi) { }  // error: synch of value, unpredictable result synchronized (obj2) { }  // unpredictable result Complex qq = pi; qq = null;  // possible NPE; warning: “null-unsafe" qq = (Complex) obj;  // warning: “null-unsafe" qq = Complex.cast(obj);  // OK @SuppressWarnings("null-unsafe")   Complex empty = null;  // possible NPE qq = empty;  // possible NPE (null pollution) The Payoffs It follows from this that either the JVM or the java compiler can replace boxed value-type values with unboxed ones, without affecting normal computations.  Fields and variables of value types can be split into their unboxed components.  Non-static methods on value types can be transformed into static methods which take the components as value parameters. Some common questions arise around this point in any discussion of value types. Why burden the programmer with all these extra rules?  Why not detect programs automagically and perform unboxing transparently?  The answer is that it is easy to break the rules accidently unless they are agreed to by the programmer and enforced.  Automatic unboxing optimizations are tantalizing but (so far) unreachable ideal.  In the current state of the art, it is possible exhibit benchmarks in which automatic unboxing provides the desired effects, but it is not possible to provide a JVM with a performance model that assures the programmer when unboxing will occur.  This is why I’m writing this note, to enlist help from, and provide assurances to, the programmer.  Basically, I’m shooting for a good set of user-supplied “pragmas” to frame the desired optimization. Again, the important thing is that the unboxing must be done reliably, or else programmers will have no reason to work with the extra complexity of the value-safety rules.  There must be a reasonably stable performance model, wherein using a value type has approximately the same performance characteristics as writing the unboxed components as separate Java variables. There are some rough corners to the present scheme.  Since Java fields and array elements are initialized to null, value-type computations which incorporate uninitialized variables can produce null pointer exceptions.  One workaround for this is to require such variables to be null-tested, and the result replaced with a suitable all-zero value of the value type.  That is what the “cast” method does above. Generically typed APIs like List<T> will continue to manipulate boxed values always, at least until we figure out how to do reification of generic type instances.  Use of such APIs will elicit warnings until their type parameters (and/or relevant members) are annotated or typed as value-safe.  Retrofitting List<T> is likely to expose flaws in the present scheme, which we will need to engineer around.  Here are a couple of first approaches: public interface java.util.List<@ValueSafe T> extends Collection<T> { … public interface java.util.List<T extends Object|ValueType> extends Collection<T> { … (The second approach would require disjunctive types, in which value-safety is “contagious” from the constituent types.) With more transformations, the return value types of methods can also be unboxed.  This may require significant bytecode-level transformations, and would work best in the presence of a bytecode representation for multiple value groups, which I have proposed elsewhere under the title “Tuples in the VM”. But for starters, the JVM can apply this transformation under the covers, to internally compiled methods.  This would give a way to express multiple return values and structured return values, which is a significant pain-point for Java programmers, especially those who work with low-level structure types favored by modern vector and graphics processors.  The lack of multiple return values has a strong distorting effect on many Java APIs. Even if the JVM fails to unbox a value, there is still potential benefit to the value type.  Clustered computing systems something have copy operations (serialization or something similar) which apply implicitly to command operands.  When copying JVM objects, it is extremely helpful to know when an object’s identity is important or not.  If an object reference is a copied operand, the system may have to create a proxy handle which points back to the original object, so that side effects are visible.  Proxies must be managed carefully, and this can be expensive.  On the other hand, value types are exactly those types which a JVM can “copy and forget” with no downside. Array types are crucial to bulk data interfaces.  (As data sizes and rates increase, bulk data becomes more important than scalar data, so arrays are definitely accompanying us into the future of computing.)  Value types are very helpful for adding structure to bulk data, so a successful value type mechanism will make it easier for us to express richer forms of bulk data. Unboxing arrays (i.e., arrays containing unboxed values) will provide better cache and memory density, and more direct data movement within clustered or heterogeneous computing systems.  They require the deepest transformations, relative to today’s JVM.  There is an impedance mismatch between value-type arrays and Java’s covariant array typing, so compromises will need to be struck with existing Java semantics.  It is probably worth the effort, since arrays of unboxed value types are inherently more memory-efficient than standard Java arrays, which rely on dependent pointer chains. It may be sufficient to extend the “value-safe” concept to array declarations, and allow low-level transformations to change value-safe array declarations from the standard boxed form into an unboxed tuple-based form.  Such value-safe arrays would not be convertible to Object[] arrays.  Certain connection points, such as Arrays.copyOf and System.arraycopy might need additional input/output combinations, to allow smooth conversion between arrays with boxed and unboxed elements. Alternatively, the correct solution may have to wait until we have enough reification of generic types, and enough operator overloading, to enable an overhaul of Java arrays. Implicit Method Definitions The example of class Complex above may be unattractively complex.  I believe most or all of the elements of the example class are required by the logic of value types. If this is true, a programmer who writes a value type will have to write lots of error-prone boilerplate code.  On the other hand, I think nearly all of the code (except for the domain-specific parts like plus and minus) can be implicitly generated. Java has a rule for implicitly defining a class’s constructor, if no it defines no constructors explicitly.  Likewise, there are rules for providing default access modifiers for interface members.  Because of the highly regular structure of value types, it might be reasonable to perform similar implicit transformations on value types.  Here’s an example of a “highly implicit” definition of a complex number type: public class Complex implements ValueType {  // implicitly final     public double re, im;  // implicitly public final     //implicit methods are defined elementwise from te fields:     //  toString, asList, equals(2), hashCode, valueOf, cast     //optionally, explicit methods (plus, abs, etc.) would go here } In other words, with the right defaults, a simple value type definition can be a one-liner.  The observant reader will have noticed the similarities (and suitable differences) between the explicit methods above and the corresponding methods for List<T>. Another way to abbreviate such a class would be to make an annotation the primary trigger of the functionality, and to add the interface(s) implicitly: public @ValueType class Complex { … // implicitly final, implements ValueType (But to me it seems better to communicate the “magic” via an interface, even if it is rooted in an annotation.) Implicitly Defined Value Types So far we have been working with nominal value types, which is to say that the sequence of typed components is associated with a name and additional methods that convey the intention of the programmer.  A simple ordered pair of floating point numbers can be variously interpreted as (to name a few possibilities) a rectangular or polar complex number or Cartesian point.  The name and the methods convey the intended meaning. But what if we need a truly simple ordered pair of floating point numbers, without any further conceptual baggage?  Perhaps we are writing a method (like “divideAndRemainder”) which naturally returns a pair of numbers instead of a single number.  Wrapping the pair of numbers in a nominal type (like “QuotientAndRemainder”) makes as little sense as wrapping a single return value in a nominal type (like “Quotient”).  What we need here are structural value types commonly known as tuples. For the present discussion, let us assign a conventional, JVM-friendly name to tuples, roughly as follows: public class java.lang.tuple.$DD extends java.lang.tuple.Tuple {      double $1, $2; } Here the component names are fixed and all the required methods are defined implicitly.  The supertype is an abstract class which has suitable shared declarations.  The name itself mentions a JVM-style method parameter descriptor, which may be “cracked” to determine the number and types of the component fields. The odd thing about such a tuple type (and structural types in general) is it must be instantiated lazily, in response to linkage requests from one or more classes that need it.  The JVM and/or its class loaders must be prepared to spin a tuple type on demand, given a simple name reference, $xyz, where the xyz is cracked into a series of component types.  (Specifics of naming and name mangling need some tasteful engineering.) Tuples also seem to demand, even more than nominal types, some support from the language.  (This is probably because notations for non-nominal types work best as combinations of punctuation and type names, rather than named constructors like Function3 or Tuple2.)  At a minimum, languages with tuples usually (I think) have some sort of simple bracket notation for creating tuples, and a corresponding pattern-matching syntax (or “destructuring bind”) for taking tuples apart, at least when they are parameter lists.  Designing such a syntax is no simple thing, because it ought to play well with nominal value types, and also with pre-existing Java features, such as method parameter lists, implicit conversions, generic types, and reflection.  That is a task for another day. Other Use Cases Besides complex numbers and simple tuples there are many use cases for value types.  Many tuple-like types have natural value-type representations. These include rational numbers, point locations and pixel colors, and various kinds of dates and addresses. Other types have a variable-length ‘tail’ of internal values. The most common example of this is String, which is (mathematically) a sequence of UTF-16 character values. Similarly, bit vectors, multiple-precision numbers, and polynomials are composed of sequences of values. Such types include, in their representation, a reference to a variable-sized data structure (often an array) which (somehow) represents the sequence of values. The value type may also include ’header’ information. Variable-sized values often have a length distribution which favors short lengths. In that case, the design of the value type can make the first few values in the sequence be direct ’header’ fields of the value type. In the common case where the header is enough to represent the whole value, the tail can be a shared null value, or even just a null reference. Note that the tail need not be an immutable object, as long as the header type encapsulates it well enough. This is the case with String, where the tail is a mutable (but never mutated) character array. Field types and their order must be a globally visible part of the API.  The structure of the value type must be transparent enough to have a globally consistent unboxed representation, so that all callers and callees agree about the type and order of components  that appear as parameters, return types, and array elements.  This is a trade-off between efficiency and encapsulation, which is forced on us when we remove an indirection enjoyed by boxed representations.  A JVM-only transformation would not care about such visibility, but a bytecode transformation would need to take care that (say) the components of complex numbers would not get swapped after a redefinition of Complex and a partial recompile.  Perhaps constant pool references to value types need to declare the field order as assumed by each API user. This brings up the delicate status of private fields in a value type.  It must always be possible to load, store, and copy value types as coordinated groups, and the JVM performs those movements by moving individual scalar values between locals and stack.  If a component field is not public, what is to prevent hostile code from plucking it out of the tuple using a rogue aload or astore instruction?  Nothing but the verifier, so we may need to give it more smarts, so that it treats value types as inseparable groups of stack slots or locals (something like long or double). My initial thought was to make the fields always public, which would make the security problem moot.  But public is not always the right answer; consider the case of String, where the underlying mutable character array must be encapsulated to prevent security holes.  I believe we can win back both sides of the tradeoff, by training the verifier never to split up the components in an unboxed value.  Just as the verifier encapsulates the two halves of a 64-bit primitive, it can encapsulate the the header and body of an unboxed String, so that no code other than that of class String itself can take apart the values. Similar to String, we could build an efficient multi-precision decimal type along these lines: public final class DecimalValue extends ValueType {     protected final long header;     protected private final BigInteger digits;     public DecimalValue valueOf(int value, int scale) {         assert(scale >= 0);         return new DecimalValue(((long)value << 32) + scale, null);     }     public DecimalValue valueOf(long value, int scale) {         if (value == (int) value)             return valueOf((int)value, scale);         return new DecimalValue(-scale, new BigInteger(value));     } } Values of this type would be passed between methods as two machine words. Small values (those with a significand which fits into 32 bits) would be represented without any heap data at all, unless the DecimalValue itself were boxed. (Note the tension between encapsulation and unboxing in this case.  It would be better if the header and digits fields were private, but depending on where the unboxing information must “leak”, it is probably safer to make a public revelation of the internal structure.) Note that, although an array of Complex can be faked with a double-length array of double, there is no easy way to fake an array of unboxed DecimalValues.  (Either an array of boxed values or a transposed pair of homogeneous arrays would be reasonable fallbacks, in a current JVM.)  Getting the full benefit of unboxing and arrays will require some new JVM magic. Although the JVM emphasizes portability, system dependent code will benefit from using machine-level types larger than 64 bits.  For example, the back end of a linear algebra package might benefit from value types like Float4 which map to stock vector types.  This is probably only worthwhile if the unboxing arrays can be packed with such values. More Daydreams A more finely-divided design for dynamic enforcement of value safety could feature separate marker interfaces for each invariant.  An empty marker interface Unsynchronizable could cause suitable exceptions for monitor instructions on objects in marked classes.  More radically, a Interchangeable marker interface could cause JVM primitives that are sensitive to object identity to raise exceptions; the strangest result would be that the acmp instruction would have to be specified as raising an exception. @ValueSafe public interface ValueType extends java.io.Serializable,         Unsynchronizable, Interchangeable { … public class Complex implements ValueType {     // inherits Serializable, Unsynchronizable, Interchangeable, @ValueSafe     … It seems possible that Integer and the other wrapper types could be retro-fitted as value-safe types.  This is a major change, since wrapper objects would be unsynchronizable and their references interchangeable.  It is likely that code which violates value-safety for wrapper types exists but is uncommon.  It is less plausible to retro-fit String, since the prominent operation String.intern is often used with value-unsafe code. We should also reconsider the distinction between boxed and unboxed values in code.  The design presented above obscures that distinction.  As another thought experiment, we could imagine making a first class distinction in the type system between boxed and unboxed representations.  Since only primitive types are named with a lower-case initial letter, we could define that the capitalized version of a value type name always refers to the boxed representation, while the initial lower-case variant always refers to boxed.  For example: complex pi = complex.valueOf(Math.PI, 0); Complex boxPi = pi;  // convert to boxed myList.add(boxPi); complex z = myList.get(0);  // unbox Such a convention could perhaps absorb the current difference between int and Integer, double and Double. It might also allow the programmer to express a helpful distinction among array types. As said above, array types are crucial to bulk data interfaces, but are limited in the JVM.  Extending arrays beyond the present limitations is worth thinking about; for example, the Maxine JVM implementation has a hybrid object/array type.  Something like this which can also accommodate value type components seems worthwhile.  On the other hand, does it make sense for value types to contain short arrays?  And why should random-access arrays be the end of our design process, when bulk data is often sequentially accessed, and it might make sense to have heterogeneous streams of data as the natural “jumbo” data structure.  These considerations must wait for another day and another note. More Work It seems to me that a good sequence for introducing such value types would be as follows: Add the value-safety restrictions to an experimental version of javac. Code some sample applications with value types, including Complex and DecimalValue. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. A staggered roll-out like this would decouple language changes from bytecode changes, which is always a convenient thing. A similar investigation should be applied (concurrently) to array types.  In this case, it seems to me that the starting point is in the JVM: Add an experimental unboxing array data structure to a production JVM, perhaps along the lines of Maxine hybrids.  No bytecode or language support is required at first; everything can be done with encapsulated unsafe operations and/or method handles. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. That’s enough musing me for now.  Back to work!

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  • Try out Windows Phone 7 on your PC today

    - by Matthew Guay
    Anticipation has been building for the new Windows Phone 7 Series ever since Microsoft unveiled it at the Mobile World Congress in February.  Now, thanks to free developer tools, you can get a first-hand experience of the basic Windows Phone 7 Series devices on your PC. Windows Phone 7 Series represents a huge change in the mobile field for Microsoft, bringing the acclaimed Zune HD UI to an innovative phone platform.  Windows Mobile has often been criticized for being behind other Smartphone platforms, but Microsoft seeks to regain the lead with this new upcoming release.  A platform must have developers behind it to be useful, so they have released a full set of free development tools so anyone can make apps for it today.  Or, if you simply want to play with Windows Phone 7, you can use the included emulator to try out the new Metro UI.  Here’s how to do this today on your Vista or 7 computer. Please note: These tools are a Customer Technology Preview release, so only install them if you’re comfortable using pre-release software. Getting Started First, download the Windows Phone Developer Tools CTP (link below), and run the installer.  This will install the Customer Technology Preview (CTP) versions of Visual Studio 2010 Express for Windows Phone, Windows Phone Emulator, Silverlight for Windows Phone, and XNA 4.0 Game Studio on your computer, all of which are required and cannot be installed individually. Accept the license agreement when prompted. Click “Install Now” to install the tools you need.  The only setup customization option is where to save the files, so choose Customize if you need to do so. Setup will now automatically download and install the components you need, and will additionally download either 32 or 64 bit programs depending on your operating system. About halfway thorough the installation, you’ll be prompted to reboot your system.  Once your computer is rebooted, setup will automatically resume without further input.   When setup is finished, click “Run the Product Now” to get started. Running Windows Phone 7 on your PC Now that you’ve got the Windows Phone Developer tools installed, it’s time to get the Windows Phone emulator running.  If you clicked “Run the Product Now” when the setup finished, Visual Studio 2010 Express for Windows Phone should have already started.   If not, simply enter “visual studio” in your start menu search and select “Microsoft Visual Studio 2010 Express for Windows Phone”. Now, to run the Windows Phone 7 emulator, we have to test an application.  So, even if you don’t know how to program, we can open a phone application template, and then test it to run the emulator.  First, click New Project on the left hand side of the front page. Any of the application templates would work for this, but here let’s select “Windows Phone Application”, and then click Ok. Here’s your new application template, which already contains the basic phone application framework.  This is where you’d start if you want to develop a Windows Phone app, but for now we just want to see Windows Phone 7 in action. So, to run the emulator, click Debug in the menu and then select Start Debugging. Your new application will launch inside the Windows Phone 7 Series emulator.  The default template doesn’t give us much, but it does show an example application running in Windows Phone 7.   Exploring Windows Phone 7 Click the Windows button on the emulator to go to the home screen.  Notice the Zune HD-like transition animation.  The emulator only includes Internet Explorer, your test application, and a few settings. Click the arrow on the right to see the available applications in a list. Settings lets you change the theme, regional settings, and the date and time in your emulator.  It also has an applications settings pane, but this currently isn’t populated. The Time settings shows a unique Windows Phone UI. You can return to the home screen by pressing the Windows button.  Here’s the Internet Explorer app running, with the virtual keyboard open to enter an address.  Please note that this emulator can also accept input from your keyboard, so you can enter addresses without clicking on the virtual keyboard. And here’s Google running in Internet Explorer on Windows Phone 7. Windows Phone 7 supports accelerometers, and you can simulate this in the emulator.  Click one of the rotate buttons to rotate the screen in that direction. Here’s our favorite website in Internet Explorer on Windows Phone 7 in landscape mode. All this, running right inside your Windows 7 desktop… Developer tools for Windows Phone 7 Although it may be fun to play with the Windows Phone 7 emulator, developers will be more excited to actually be able to create new and exciting apps for it.  The Windows Phone Developer Tools download includes Visual Studio Express and XNA Game Studio 4.0 which lets you create enticing games and apps for Windows Phones.  All development for Windows Phones will be in C#, Silverlight, and the XNA game framework.  Visual Studio Express for Windows Phone includes templates for these, and additionally has code samples to help you get started with development. Conclusion Many features are still not functional in this preview version, such as the search button and most of the included applications.  However, this still gives you a great way to experience firsthand the future of the Windows Phone platform.  And, for developers, this is your chance to set your mark on the Windows Phone 7 Series even before it is released to the public.  Happy playing and developing! Links Download Windows Phone Developer Tools CTP Windows Phone Developer Site Similar Articles Productive Geek Tips Keep Track of Homework Assignments with SoshikuWeekend Fun: Watch Television On Your PC With TVUPlayerEasily Manage Your Downloads with Download StatusbarCreate a Shortcut or Hotkey to Mute the System Volume in WindowsHow-To Geek on Lifehacker: How to Make Windows Vista Less Annoying TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 PCmover Professional Convert the Quick Launch Bar into a Super Application Launcher Automate Tasks in Linux with Crontab Discover New Bundled Feeds in Google Reader Play Music in Chrome by Simply Dragging a File 15 Great Illustrations by Chow Hon Lam Easily Sync Files & Folders with Friends & Family

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  • Monitor your Hard Drive’s Health with Acronis Drive Monitor

    - by Matthew Guay
    Are you worried that your computer’s hard drive could die without any warning?  Here’s how you can keep tabs on it and get the first warning signs of potential problems before you actually lose your critical data. Hard drive failures are one of the most common ways people lose important data from their computers.  As more of our memories and important documents are stored digitally, a hard drive failure can mean the loss of years of work.  Acronis Drive Monitor helps you avert these disasters by warning you at the first signs your hard drive may be having trouble.  It monitors many indicators, including heat, read/write errors, total lifespan, and more. It then notifies you via a taskbar popup or email that problems have been detected.  This early warning lets you know ahead of time that you may need to purchase a new hard drive and migrate your data before it’s too late. Getting Started Head over to the Acronis site to download Drive Monitor (link below).  You’ll need to enter your name and email, and then you can download this free tool. Also, note that the download page may ask if you want to include a trial of their for-pay backup program.  If you wish to simply install the Drive Monitor utility, click Continue without adding. Run the installer when the download is finished.  Follow the prompts and install as normal. Once it’s installed, you can quickly get an overview of your hard drives’ health.  Note that it shows 3 categories: Disk problems, Acronis backup, and Critical Events.  On our computer, we had Seagate DiskWizard, an image backup utility based on Acronis Backup, installed, and Acronis detected it. Drive Monitor stays running in your tray even when the application window is closed.  It will keep monitoring your hard drives, and will alert you if there’s a problem. Find Detailed Information About Your Hard Drives Acronis’ simple interface lets you quickly see an overview of how the drives on your computer are performing.  If you’d like more information, click the link under the description.  Here we see that one of our drives have overheated, so click Show disks to get more information. Now you can select each of your drives and see more information about them.  From the Disk overview tab that opens by default, we see that our drive is being monitored, has been running for a total of 368 days, and that it’s health is good.  However, it is running at 113F, which is over the recommended max of 107F.   The S.M.A.R.T. parameters tab gives us more detailed information about our drive.  Most users wouldn’t know what an accepted value would be, so it also shows the status.  If the value is within the accepted parameters, it will report OK; otherwise, it will show that has a problem in this area. One very interesting piece of information we can see is the total number of Power-On Hours, Start/Stop Count, and Power Cycle Count.  These could be useful indicators to check if you’re considering purchasing a second hand computer.  Simply load this program, and you’ll get a better view of how long it’s been in use. Finally, the Events tab shows each time the program gave a warning.  We can see that our drive, which had been acting flaky already, is routinely overheating even when our other hard drive was running in normal temperature ranges. Monitor Acronis Backups And Critical Errors In addition to monitoring critical stats of your hard drives, Acronis Drive Monitor also keeps up with the status of your backup software and critical events reported by Windows.  You can access these from the front page, or via the links on the left hand sidebar.  If you have any edition of any Acronis Backup product installed, it will show that it was detected.  Note that it can only monitor the backup status of the newest versions of Acronis Backup and True Image. If no Acronis backup software was installed, it will show a warning that the drive may be unprotected and will give you a link to download Acronis backup software.   If you have another backup utility installed that you wish to monitor yourself, click Configure backup monitoring, and then disable monitoring on the drives you’re monitoring yourself. Finally, you can view any detected Critical events from the Critical events tab on the left. Get Emailed When There’s a Problem One of Drive Monitor’s best features is the ability to send you an email whenever there’s a problem.  Since this program can run on any version of Windows, including the Server and Home Server editions, you can use this feature to stay on top of your hard drives’ health even when you’re not nearby.  To set this up, click Options in the top left corner. Select Alerts on the left, and then click the Change settings link to setup your email account. Enter the email address which you wish to receive alerts, and a name for the program.  Then, enter the outgoing mail server settings for your email.  If you have a Gmail account, enter the following information: Outgoing mail server (SMTP): smtp.gmail.com Port: 587 Username and Password: Your gmail address and password Check the Use encryption box, and then select TLS from the encryption options.   It will now send a test message to your email account, so check and make sure it sent ok. Now you can choose to have the program automatically email you when warnings and critical alerts appear, and also to have it send regular disk status reports.   Conclusion Whether you’ve got a brand new hard drive or one that’s seen better days, knowing the real health of your it is one of the best ways to be prepared before disaster strikes.  It’s no substitute for regular backups, but can help you avert problems.  Acronis Drive Monitor is a nice tool for this, and although we wish it wasn’t so centered around their backup offerings, we still found it a nice tool. Link Download Acronis Drive Monitor (registration required) Similar Articles Productive Geek Tips Quick Tip: Change Monitor Timeout From Command LineAnalyze and Manage Hard Drive Space with WinDirStatMonitor CPU, Memory, and Disk IO In Windows 7 with Taskbar MetersDefrag Multiple Hard Drives At Once In WindowsFind Your Missing USB Drive on Windows XP TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips HippoRemote Pro 2.2 Xobni Plus for Outlook All My Movies 5.9 CloudBerry Online Backup 1.5 for Windows Home Server Windows 7’s WordPad is Actually Good Greate Image Viewing and Management with Zoner Photo Studio Free Windows Media Player Plus! – Cool WMP Enhancer Get Your Team’s World Cup Schedule In Google Calendar Backup Drivers With Driver Magician TubeSort: YouTube Playlist Organizer

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  • Regression testing with Selenium GRID

    - by Ben Adderson
    A lot of software teams out there are tasked with supporting and maintaining systems that have grown organically over time, and the web team here at Red Gate is no exception. We're about to embark on our first significant refactoring endeavour for some time, and as such its clearly paramount that the code be tested thoroughly for regressions. Unfortunately we currently find ourselves with a codebase that isn't very testable - the three layers (database, business logic and UI) are currently tightly coupled. This leaves us with the unfortunate problem that, in order to confidently refactor the code, we need unit tests. But in order to write unit tests, we need to refactor the code :S To try and ease the initial pain of decoupling these layers, I've been looking into the idea of using UI automation to provide a sort of system-level regression test suite. The idea being that these tests can help us identify regressions whilst we work towards a more testable codebase, at which point the more traditional combination of unit and integration tests can take over. Ending up with a strong battery of UI tests is also a nice bonus :) Following on from my previous posts (here, here and here) I knew I wanted to use Selenium. I also figured that this would be a good excuse to put my xUnit [Browser] attribute to good use. Pretty quickly, I had a raft of tests that looked like the following (this particular example uses Reflector Pro). In a nut shell the test traverses our shopping cart and, for a particular combination of number of users and months of support, checks that the price calculations all come up with the correct values. [BrowserTheory] [Browser(Browsers.Firefox3_6, "http://www.red-gate.com")] public void Purchase1UserLicenceNoSupport(SeleniumProvider seleniumProvider) {     //Arrange     _browser = seleniumProvider.GetBrowser();     _browser.Open("http://www.red-gate.com/dynamic/shoppingCart/ProductOption.aspx?Product=ReflectorPro");                  //Act     _browser = ShoppingCartHelpers.TraverseShoppingCart(_browser, 1, 0, ".NET Reflector Pro");     //Assert     var priceResult = PriceHelpers.GetNewPurchasePrice(db, "ReflectorPro", 1, 0, Currencies.Euros);         Assert.Equal(priceResult.Price, _browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl01_Price"));     Assert.Equal(priceResult.Tax, _browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl02_Tax"));     Assert.Equal(priceResult.Total, _browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl02_Total")); } These tests are pretty concise, with much of the common code in the TraverseShoppingCart() and GetNewPurchasePrice() methods. The (inevitable) problem arose when it came to execute these tests en masse. Selenium is a very slick tool, but it can't mask the fact that UI automation is very slow. To give you an idea, the set of cases that covers all of our products, for all combinations of users and support, came to 372 tests (for now only considering purchases in dollars). In the world of automated integration tests, that's a very manageable number. For unit tests, it's a trifle. However for UI automation, those 372 tests were taking just over two hours to run. Two hours may not sound like a lot, but those cases only cover one of the three currencies we deal with, and only one of the many different ways our systems can be asked to calculate a price. It was already pretty clear at this point that in order for this approach to be viable, I was going to have to find a way to speed things up. Up to this point I had been using Selenium Remote Control to automate Firefox, as this was the approach I had used previously and it had worked well. Fortunately,  the guys at SeleniumHQ also maintain a tool for executing multiple Selenium RC tests in parallel: Selenium Grid. Selenium Grid uses a central 'hub' to handle allocation of Selenium tests to individual RCs. The Remote Controls simply register themselves with the hub when they start, and then wait to be assigned work. The (for me) really clever part is that, as far as the client driver library is concerned, the grid hub looks exactly the same as a vanilla remote control. To create a new browser session against Selenium RC, the following C# code suffices: new DefaultSelenium("localhost", 4444, "*firefox", "http://www.red-gate.com"); This assumes that the RC is running on the local machine, and is listening on port 4444 (the default). Assuming the hub is running on your local machine, then to create a browser session in Selenium Grid, via the hub rather than directly against the control, the code is exactly the same! Behind the scenes, the hub will take this request and hand it off to one of the registered RCs that provides the "*firefox" execution environment. It will then pass all communications back and forth between the test runner and the remote control transparently. This makes running existing RC tests on a Selenium Grid a piece of cake, as the developers intended. For a more detailed description of exactly how Selenium Grid works, see this page. Once I had a test environment capable of running multiple tests in parallel, I needed a test runner capable of doing the same. Unfortunately, this does not currently exist for xUnit (boo!). MbUnit on the other hand, has the concept of concurrent execution baked right into the framework. So after swapping out my assembly references, and fixing up the resulting mismatches in assertions, my example test now looks like this: [Test] public void Purchase1UserLicenceNoSupport() {    //Arrange    ISelenium browser = BrowserHelpers.GetBrowser();    var db = DbHelpers.GetWebsiteDBDataContext();    browser.Start();    browser.Open("http://www.red-gate.com/dynamic/shoppingCart/ProductOption.aspx?Product=ReflectorPro");                 //Act     browser = ShoppingCartHelpers.TraverseShoppingCart(browser, 1, 0, ".NET Reflector Pro");    var priceResult = PriceHelpers.GetNewPurchasePrice(db, "ReflectorPro", 1, 0, Currencies.Euros);    //Assert     Assert.AreEqual(priceResult.Price, browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl01_Price"));     Assert.AreEqual(priceResult.Tax, browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl02_Tax"));     Assert.AreEqual(priceResult.Total, browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl02_Total")); } This is pretty much the same as the xUnit version. The exceptions are that the attributes have changed,  the //Arrange phase now has to handle setting up the ISelenium object, as the attribute that previously did this has gone away, and the test now sets up its own database connection. Previously I was using a shared database connection, but this approach becomes more complicated when tests are being executed concurrently. To avoid complexity each test has its own connection, which it is responsible for closing. For the sake of readability, I snipped out the code that closes the browser session and the db connection at the end of the test. With all that done, there was only one more step required before the tests would execute concurrently. It is necessary to tell the test runner which tests are eligible to run in parallel, via the [Parallelizable] attribute. This can be done at the test, fixture or assembly level. Since I wanted to run all tests concurrently, I marked mine at the assembly level in the AssemblyInfo.cs using the following: [assembly: DegreeOfParallelism(3)] [assembly: Parallelizable(TestScope.All)] The second attribute marks all tests in the assembly as [Parallelizable], whilst the first tells the test runner how many concurrent threads to use when executing the tests. I set mine to three since I was using 3 RCs in separate VMs. With everything now in place, I fired up the Icarus* test runner that comes with MbUnit. Executing my 372 tests three at a time instead of one at a time reduced the running time from 2 hours 10 minutes, to 55 minutes, that's an improvement of about 58%! I'd like to have seen an improvement of 66%, but I can understand that either inefficiencies in the hub code, my test environment or the test runner code (or some combination of all three most likely) contributes to a slightly diminished improvement. That said, I'd love to hear about any experience you have in upping this efficiency. Ultimately though, it was a saving that was most definitely worth having. It makes regression testing via UI automation a far more plausible prospect. The other obvious point to make is that this approach scales far better than executing tests serially. So if ever we need to improve performance, we just register additional RC's with the hub, and up the DegreeOfParallelism. *This was just my personal preference for a GUI runner. The MbUnit/Gallio installer also provides a command line runner, a TestDriven.net runner, and a Resharper 4.5 runner. For now at least, Resharper 5 isn't supported.

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  • RSS feeds in Orchard

    - by Bertrand Le Roy
    When we added RSS to Orchard, we wanted to make it easy for any module to expose any contents as a feed. We also wanted the rendering of the feed to be handled by Orchard in order to minimize the amount of work from the module developer. A typical example of such feed exposition is of course blog feeds. We have an IFeedManager interface for which you can get the built-in implementation through dependency injection. Look at the BlogController constructor for an example: public BlogController( IOrchardServices services, IBlogService blogService, IBlogSlugConstraint blogSlugConstraint, IFeedManager feedManager, RouteCollection routeCollection) { If you look a little further in that same controller, in the Item action, you’ll see a call to the Register method of the feed manager: _feedManager.Register(blog); This in reality is a call into an extension method that is specialized for blogs, but we could have made the two calls to the actual generic Register directly in the action instead, that is just an implementation detail: feedManager.Register(blog.Name, "rss", new RouteValueDictionary { { "containerid", blog.Id } }); feedManager.Register(blog.Name + " - Comments", "rss", new RouteValueDictionary { { "commentedoncontainer", blog.Id } }); What those two effective calls are doing is to register two feeds: one for the blog itself and one for the comments on the blog. For each call, the name of the feed is provided, then we have the type of feed (“rss”) and some values to be injected into the generic RSS route that will be used later to route the feed to the right providers. This is all you have to do to expose a new feed. If you’re only interested in exposing feeds, you can stop right there. If on the other hand you want to know what happens after that under the hood, carry on. What happens after that is that the feedmanager will take care of formatting the link tag for the feed (see FeedManager.GetRegisteredLinks). The GetRegisteredLinks method itself will be called from a specialized filter, FeedFilter. FeedFilter is an MVC filter and the event we’re interested in hooking into is OnResultExecuting, which happens after the controller action has returned an ActionResult and just before MVC executes that action result. In other words, our feed registration has already been called but the view is not yet rendered. Here’s the code for OnResultExecuting: model.Zones.AddAction("head:after", html => html.ViewContext.Writer.Write( _feedManager.GetRegisteredLinks(html))); This is another piece of code whose execution is differed. It is saying that whenever comes time to render the “head” zone, this code should be called right after. The code itself is rendering the link tags. As a result of all that, here’s what can be found in an Orchard blog’s head section: <link rel="alternate" type="application/rss+xml"     title="Tales from the Evil Empire"     href="/rss?containerid=5" /> <link rel="alternate" type="application/rss+xml"     title="Tales from the Evil Empire - Comments"     href="/rss?commentedoncontainer=5" /> The generic action that these two feeds point to is Index on FeedController. That controller has three important dependencies: an IFeedBuilderProvider, an IFeedQueryProvider and an IFeedItemProvider. Different implementations of these interfaces can provide different formats of feeds, such as RSS and Atom. The Match method enables each of the competing providers to provide a priority for themselves based on arbitrary criteria that can be found on the FeedContext. This means that a provider can be selected based not only on the desired format, but also on the nature of the objects being exposed as a feed or on something even more arbitrary such as the destination device (you could imagine for example giving shorter text only excerpts of posts on mobile devices, and full HTML on desktop). The key here is extensibility and dynamic competition and collaboration from unknown and loosely coupled parts. You’ll find this pattern pretty much everywhere in the Orchard architecture. The RssFeedBuilder implementation of IFeedBuilderProvider is also a regular controller with a Process action that builds a RssResult, which is itself a thin ActionResult wrapper around an XDocument. Let’s get back to the FeedController’s Index action. After having called into each known feed builder to get its priority on the currently requested feed, it will select the one with the highest priority. The next thing it needs to do is to actually fetch the data for the feed. This again is a collaborative effort from a priori unknown providers, the implementations of IFeedQueryProvider. There are several implementations by default in Orchard, the choice of which is again done through a Match method. ContainerFeedQuery for example chimes in when a “containerid” parameter is found in the context (see URL in the link tag above): public FeedQueryMatch Match(FeedContext context) { var containerIdValue = context.ValueProvider.GetValue("containerid"); if (containerIdValue == null) return null; return new FeedQueryMatch { FeedQuery = this, Priority = -5 }; } The actual work is done in the Execute method, which finds the right container content item in the Orchard database and adds elements for each of them. In other words, the feed query provider knows how to retrieve the list of content items to add to the feed. The last step is to translate each of the content items into feed entries, which is done by implementations of IFeedItemBuilder. There is no Match method this time. Instead, all providers are called with the collection of items (or more accurately with the FeedContext, but this contains the list of items, which is what’s relevant in most cases). Each provider can then choose to pick those items that it knows how to treat and transform them into the format requested. This enables the construction of heterogeneous feeds that expose content items of various types into a single feed. That will be extremely important when you’ll want to expose a single feed for all your site. So here are feeds in Orchard in a nutshell. The main point here is that there is a fair number of components involved, with some complexity in implementation in order to allow for extreme flexibility, but the part that you use to expose a new feed is extremely simple and light: declare that you want your content exposed as a feed and you’re done. There are cases where you’ll have to dive in and provide new implementations for some or all of the interfaces involved, but that requirement will only arise as needed. For example, you might need to create a new feed item builder to include your custom content type but that effort will be extremely focused on the specialized task at hand. The rest of the system won’t need to change. So what do you think?

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  • Copying Columns from Grid to Clipboard in SQL Developer

    - by thatjeffsmith
    There are several ways to get data from a query or a table|view to the clipboard. You know the tried and true, copy and paste. But what if you only want one or more columns, not every column? There are several ways to do this, let’s see if we can’t identify all of them. Write your query to only include the data you want Obvious? Yes. Needed to be said? Definitely. The best tuning tip is to only ask for the data you need, only when you absolutely need it. But let’s look at a few more practical ways to do this. Hide the unwanted columns Mouse right click on an column header. In the context menu, select ‘Columns.’ Hide the columns you don’t want. Copy and paste. WYSIWYG Grids, Hide Columns and Filter Rows Mouse select the columns Obvious, but a bit painful. For a very large dataset, you’ll be holding down the Shift and PageDown buttons – but it works. Remember to use Ctrl+Shift+C to get the column headers with the data. Use the Export Wizard This used to be called ‘Unload’ – agreed, not a great name. So, we changed it. In a grid, right mouse click on the data, and on the context menu, select ‘Export…’ Select your format – I suggest ‘delimited’ or ‘fixed’ for copying data to the clipboard. You can export to the clipboard, yes you can! Click ‘Next.’ Click in the Columns dialog, and choose the columns you want copied. Trim the columns you don't want copied Click ‘Finish.’ Alt or Ctrl tab to your window or application of choice. And Paste! "FIRST_NAME" "LAST_NAME" "Donald" "OConnell" "Douglas" "Grant" "Jennifer" "Whalen" "Pat" "Fay" "Susan" "Mavris" "William" "Gietz" "Alexander" "Hunold" "Bruce" "Ernst" "David" "Austin" "Valli" "Pataballa" "Diana" "Lorentz" "Daniel" "Faviet" "John" "Chen" "Ismael" "Sciarra" "Jose Manuel" "Urman" "Luis" "Popp" "Alexander" "Khoo" "Shelli" "Baida" "Sigal" "Tobias" "Guy" "Himuro" "Karen" "Colmenares" "Matthew" "Weiss" "Adam" "Fripp" "Payam" "Kaufling" "Shanta" "Vollman" "Kevin" "Mourgos" "Julia" "Nayer" "Irene" "Mikkilineni" ... There’s probably at least 2 or 3 more ways, but… But, try these and let me know how we can improve things. I’ve already gotten a request to be able to include the SQL text used to populate the dataset on the the copy to clipboard, and it’s now on our to-do list

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