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  • Does replacing statements by expressions using the C++ comma operator could allow more compiler opti

    - by Gabriel Cuvillier
    The C++ comma operator is used to chain individual expressions, yielding the value of the last executed expression as the result. For example the skeleton code (6 statements, 6 expressions): step1; step2; if (condition) step3; return step4; else return step5; May be rewritten to: (1 statement, 6 expressions) return step1, step2, condition? step3, step4 : step5; I noticed that it is not possible to perform step-by-step debugging of such code, as the expression chain seems to be executed as a whole. Does it means that the compiler is able to perform special optimizations which are not possible with the traditional statement approach (specially if the steps are const or inline)? Note: I'm not talking about the coding style merit of that way of expressing sequence of expressions! Just about the possible optimisations allowed by replacing statements by expressions.

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  • Platform Framework and Middle-ware

    - by Walidix
    I really want to fix the meanings of this terms.This is what I know about them: Platform: is an environment that allows an application to run and it is usually composite by hardware and software e.g. your machine with your OS installed on it. However some software stack are also called as platform like Java Platform. Framework: is design-oriented. That is, it defines a skeleton of an application type. Also it saves time by offering, through an API, the common functionalities that a kind of applications must implement. Moreover a Framework include a software components that manage the application life-cycle. Middle-ware: is a software that offers services to an application in order to let it inter-operates with other applications or supports different platforms. Middle-ware can be a part of a framework. Is there something wrong or missing ?

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  • Flickering when repainting a JPanel inside a JScrollPAne

    - by pR0Ps
    I'm having a problem with repainting a JPanel inside a JScrollPane. Basically, I'm just trying to 'wrap' my existing EditPanel (it originally extended JPanel) into a JScrollPane. It seems that the JPanel updates too often (mass flickering). How would I stop this from happening? I tried using the setIgnoreRepaint() but it didn't seem to do anything. Will this current implementation work or would I need to create another inner class to fine-tune the JPanel I'm using to display graphics? Skeleton code: public class MyProgram extends JFrame{ public MyProgram(){ super(); add(new EditPanel()); pack(); } private class EditPanel extends JScrollPane{ private JPanel graphicsPanel; public EditPanel(){ graphicsPanel = new JPanel(); } public void paintComponent(Graphics g){ graphicsPanel.revalidate(); //update the scrollpane to current panel size repaint(); Graphics g2 = graphicsPanel.getGraphics(); g2.drawImage(imageToDraw, 0, 0, null); } } }

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  • Modular HTML in Adobe AIR? Is It Possible?

    - by Greg Bulmash
    When I write HTML with a PHP backend, I usually have a single header file and a single footer file with some PHP variables in them. The base skeleton for every page calls the header, contains the body content, and then calls the footer. That way, if I want to make changes to the header sitewide, I change one file. I'm working on developing the UI in my first Adobe AIR app and I'm wondering if there's some way to include such files in an HTML based page template there. Obviously, with the file read/write abilities in AIR, I can write a Javascript routine to pull data from a header file, parse it, and inject it into a placeholder. It just seems like such a kludge. I'm thinking there's gotta be some simple way to import a block of HTML into a page without an iFrame or complex post-processor. Something like a PHP include statement or perhaps the old Server Side Includes. Any methods you guys can recommend?

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  • Is a PHP-only "cache engine" ever worth it?

    - by adsads
    I wrote a rather small skeleton for my web apps and thought that I would also add a small cache for it. It is rather simple: If the current page exists as a file in the cache and the file isn't too old, read it out and exit instead of rebuilding the page If the current page isn't cached/outdated recalc the page and save it However, the bad thing about it is: My performance tests with a page that receives 40 relatively long posts via a MySQL query said that with using the cache, it took even longer to handle a single request (1000 tests each) How can that happen? Should I just remove the complete raw-PHP cache and relieve on the availability of some PHP cache like memcached or so?

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  • jQuery variables and scope

    - by Peuge
    I am writing a jQuery plugin and am running into a few problems with regard to variables. For example I have the following skeleton structure for my plugin, which is going to act on a textbox. In my init function I want to set a variable and bind a keypress event to my textbox. That keypress event needs to call another function, in which I need the variable. Is this possible? (function($){ var methods = { init : function(options){ return this.each(function(){ var $this = $(this); var someVar = 'somevar'; $this.keypress(function(event){ //I want to call my customFunction }); }); }, customFunction : function(){ //I am wanting to access 'someVar' here }; $.fn.mynamespace = function(method){ //handle which method to call here }; })(jQuery); Many thanks in advance.

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  • SQL Alchemy: Relationship with grandson

    - by giomasce
    I'm building a SQL Alchemy structure with three different levels of objects; for example, consider a simple database to store information about some blogs: there are some Blog object, some Post object and some Comment objects. Each Post belongs to a Blog and each Comment belongs to a Post. Using backref I can automatically have the list of all Posts belonging to a Blog and similarly for Comments. I drafted a skeleton for such a structure. What I would like to do now is to have directly in Blog an array of all the Comments belonging to that Blog. I've tried a few approaches, but they don't work or even make SQL Alchemy cry in ways I can't fix. I'd think that mine is quite a frequent need, but I couldn't find anything helpful. Colud someone suggest me how to do that? Thanks.

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  • How can I configure Xcode to put '{' where I want it in generated files

    - by djhworld
    I know this is a fairly contentious issue amongst programmers, but when developing I like my IDE to position the opening curly bracket underneath the method/interface/control declaration, for illustrative purposes: - This is how Xcode automatically generates skeleton methods with the { at the end: - -(void) isTrue:(BOOL)input { if(input) { return YES; } else { return NO; } } This is how I like to lay out my code (which I believe is called the Allman style): - -(void) isTrue:(BOOL)input { if(input) { return YES; } else { return NO; } } I'm just wondering if there's any configuration switch in Xcode to enable this style of development? It's really annoying when typing out if/else statements as it tends to auto-complete the else clause with the { at the end of the line which just looks silly if you like developing with them underneath. Or am I being unreasonable? Is Objective-C supposed to adhere to a standard defined by Apple?

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  • custom implementation of interface methods

    - by Renuka
    Hello all, I have a doubt in this scenario, I have posted some example code here.... public interface a{ public void m1(); public void m2(); public void m3(); . . . public void m100(); } public class A implements a{ public void m3(){ // implementation code } // Here i need to implement only m3() method but not all 100 methods //basically i have to implement all the other 99 methods // but here i don't want to either implement or provide skeleton declarations for all //remaining.... what should i do for compiling this ???? } Could anyone help this?

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  • How to insert into data base using multi threading programming [closed]

    - by user1196650
    I am having a method and that method needs to do the following thing: It has to insert records into a database. No insert is done for the same table again. All inserts are into different tables. I need a multi threading logic which inserts the details into db using different threads. I am using oracle db and driver configuration and remaining stuff are perfect. Please help me with an efficient answer. Can anyone could provide me with a skeleton logic of the program.

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  • What is the current state of Ubuntu's transition from init scripts to Upstart?

    - by Adam Eberlin
    What is the current state of Ubuntu's transition from init.d scripts to upstart? I was curious, so I compared the contents of /etc/init.d/ to /etc/init/ on one of our development machines, which is running Ubuntu 12.04 LTS Server. # /etc/init.d/ # /etc/init/ acpid acpid.conf apache2 --------------------------- apparmor --------------------------- apport apport.conf atd atd.conf bind9 --------------------------- bootlogd --------------------------- cgroup-lite cgroup-lite.conf --------------------------- console.conf console-setup console-setup.conf --------------------------- container-detect.conf --------------------------- control-alt-delete.conf cron cron.conf dbus dbus.conf dmesg dmesg.conf dns-clean --------------------------- friendly-recovery --------------------------- --------------------------- failsafe.conf --------------------------- flush-early-job-log.conf --------------------------- friendly-recovery.conf grub-common --------------------------- halt --------------------------- hostname hostname.conf hwclock hwclock.conf hwclock-save hwclock-save.conf irqbalance irqbalance.conf killprocs --------------------------- lxc lxc.conf lxc-net lxc-net.conf module-init-tools module-init-tools.conf --------------------------- mountall.conf --------------------------- mountall-net.conf --------------------------- mountall-reboot.conf --------------------------- mountall-shell.conf --------------------------- mounted-debugfs.conf --------------------------- mounted-dev.conf --------------------------- mounted-proc.conf --------------------------- mounted-run.conf --------------------------- mounted-tmp.conf --------------------------- mounted-var.conf networking networking.conf network-interface network-interface.conf network-interface-container network-interface-container.conf network-interface-security network-interface-security.conf newrelic-sysmond --------------------------- ondemand --------------------------- plymouth plymouth.conf plymouth-log plymouth-log.conf plymouth-splash plymouth-splash.conf plymouth-stop plymouth-stop.conf plymouth-upstart-bridge plymouth-upstart-bridge.conf postgresql --------------------------- pppd-dns --------------------------- procps procps.conf rc rc.conf rc.local --------------------------- rcS rcS.conf --------------------------- rc-sysinit.conf reboot --------------------------- resolvconf resolvconf.conf rsync --------------------------- rsyslog rsyslog.conf screen-cleanup screen-cleanup.conf sendsigs --------------------------- setvtrgb setvtrgb.conf --------------------------- shutdown.conf single --------------------------- skeleton --------------------------- ssh ssh.conf stop-bootlogd --------------------------- stop-bootlogd-single --------------------------- sudo --------------------------- --------------------------- tty1.conf --------------------------- tty2.conf --------------------------- tty3.conf --------------------------- tty4.conf --------------------------- tty5.conf --------------------------- tty6.conf udev udev.conf udev-fallback-graphics udev-fallback-graphics.conf udev-finish udev-finish.conf udevmonitor udevmonitor.conf udevtrigger udevtrigger.conf ufw ufw.conf umountfs --------------------------- umountnfs.sh --------------------------- umountroot --------------------------- --------------------------- upstart-socket-bridge.conf --------------------------- upstart-udev-bridge.conf urandom --------------------------- --------------------------- ureadahead.conf --------------------------- ureadahead-other.conf --------------------------- wait-for-state.conf whoopsie whoopsie.conf To be honest, I'm not entirely sure if I'm interpreting the division of responsibilities properly, as I didn't expect to see any overlap (of what framework handles which services). So I was quite surprised to learn that there was a significant amount of overlap in service references, in addition to being unable to discern which of the two was intended to be the primary service framework. Why does there seem to be a fair amount of redundancy in individual service handling between init.d and upstart? Is something else at play here that I'm missing? What is preventing upstart from completely taking over for init.d? Is there some functionality that certain daemons require which upstart does not yet have, which are preventing some services from converting? Or is it something else entirely?

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  • Beginning with first project on game development [closed]

    - by Tsvetan
    Today is the day I am going to start my first real game project. It will be a Universe simulator. Basically, you can build anything from tiny meteor to quazars and universes. It is going to be my project for an olympiad in IT in my country and I really want to make it perfect(at least a bronze medal). So, I would like to ask some questions about organization and development methodologies. Firstly, my plan is to make a time schedule. In it I would write my plans for the next month or two(because that is the time I have). With this exact plan I hope to make my organisation at its best. Of course, if I am doing sth faster than the schedule I would involve more features for the game and/or continue with the tempo I have. Also, for the organisation I would make a basic pseudocode(maybe) and just rewrite it so it is compilable. Like a basic skeleton of everything. The last is an idea I tought of in the moment, but if it is good I will use it. Secondly, for the development methodologies, obviously, I think of making object-oriented code and make everything perfect(a lot of testing, good code, documentation etc.). Also, I am going to make my own menu system(I read that OpenGL hasn't got very good one). Maybe I would implement it with an xml file, holding the info about position of buttons, text boxes, images and everything. Maybe I would do a specific CSS for it and so on. I think that is very good way of doing the menu system, because it makes the presentation layer separate of the logic. But, if there is a better way, I would do it the better way. For the logic, well, I don't have much to say. OO code, testing, debuging, good and fast algorithms and so on. Also, a good documentation must be written and this is the area I need to make some research in. I think that is for now. I hope I have been enough descriptive. If more questions come on my mind, I will ask them. Edit: I think of blogging every part of the project, or at least writing down everything in a file or something like that. My question is: Is my plan of how to do everything around the project good? And if not, what is necessary to be improved and what other things I can involve for making the project good.

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  • Torchlight Black Screen and doesn't show up

    - by Lelouch Reyiz
    When I open it in full screen I get a black screen that covers whole screen,in windowed mode middle of screen.Here is a video: https://copy.com/fvrGw7QIJ8Z0 Terminal Output: alperen@alperen-Inspiron-N5010 /usr/local/games/Torchlight $ ./Torchlight.bin.x86_64 Creating resource group General Creating resource group Internal Creating resource group Autodetect SceneManagerFactory for type 'DefaultSceneManager' registered. Registering ResourceManager for type Material Registering ResourceManager for type Mesh Registering ResourceManager for type Skeleton MovableObjectFactory for type 'ParticleSystem' registered. OverlayElementFactory for type Panel registered. OverlayElementFactory for type BorderPanel registered. OverlayElementFactory for type TextArea registered. Registering ResourceManager for type Font ArchiveFactory for archive type FileSystem registered. ArchiveFactory for archive type Zip registered. FreeImage version: 3.13.1 This program uses FreeImage, a free, open source image library supporting all common bitmap formats. See http://freeimage.sourceforge.net for details Supported formats: bmp,ico,jpg,jif,jpeg,jpe,jng,koa,iff,lbm,mng,pbm,pbm,pcd,pcx,pgm,pgm,png,ppm,ppm,ras,tga,targa,tif,tiff,wap,wbmp,wbm,psd,cut,xbm,xpm,gif,hdr,g3,sgi,exr,j2k,j2c,jp2,pfm,pct,pict,pic,bay,bmq,cr2,crw,cs1,dc2,dcr,dng,erf,fff,hdr,k25,kdc,mdc,mos,mrw,nef,orf,pef,pxn,raf,raw,rdc,sr2,srf,arw,3fr,cine,ia,kc2,mef,nrw,qtk,rw2,sti,drf,dsc,ptx,cap,iiq,rwz DDS codec registering Registering ResourceManager for type HighLevelGpuProgram Registering ResourceManager for type Compositor MovableObjectFactory for type 'Entity' registered. MovableObjectFactory for type 'Light' registered. MovableObjectFactory for type 'BillboardSet' registered. MovableObjectFactory for type 'ManualObject' registered. MovableObjectFactory for type 'BillboardChain' registered. MovableObjectFactory for type 'RibbonTrail' registered. Loading library lib64/OGRE/RenderSystem_GL Installing plugin: GL RenderSystem OpenGL Rendering Subsystem created. Plugin successfully installed Loading library lib64/OGRE/Plugin_ParticleFX Installing plugin: ParticleFX Particle Emitter Type 'Point' registered Particle Emitter Type 'Box' registered Particle Emitter Type 'Ellipsoid' registered Particle Emitter Type 'Cylinder' registered Particle Emitter Type 'Ring' registered Particle Emitter Type 'HollowEllipsoid' registered Particle Affector Type 'LinearForce' registered Particle Affector Type 'ColourFader' registered Particle Affector Type 'ColourFader2' registered Particle Affector Type 'ColourImage' registered Particle Affector Type 'ColourInterpolator' registered Particle Affector Type 'Scaler' registered Particle Affector Type 'Rotator' registered Particle Affector Type 'DirectionRandomiser' registered Particle Affector Type 'DeflectorPlane' registered Plugin successfully installed Loading library lib64/OGRE/Plugin_OctreeSceneManager Installing plugin: Octree & Terrain Scene Manager Plugin successfully installed *-*-* OGRE Initialising *-*-* Version 1.6.5 (Shoggoth) terminate called after throwing an instance of 'std::out_of_range' what(): basic_string::substr Error: signal: 6 ./Torchlight.bin.x86_64(_ZN10LinuxUtils13crash_handlerEi+0x25)[0x17eb6f5] /lib/x86_64-linux-gnu/libc.so.6(+0x37000)[0x7fc647877000] /lib/x86_64-linux-gnu/libc.so.6(gsignal+0x39)[0x7fc647876f89] /lib/x86_64-linux-gnu/libc.so.6(abort+0x148)[0x7fc64787a398] /usr/lib/x86_64-linux-gnu/libstdc++.so.6(_ZN9__gnu_cxx27__verbose_terminate_handlerEv+0x155)[0x7fc6481826b5] /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0x5e836)[0x7fc648180836] /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0x5e863)[0x7fc648180863] /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0x5eaa2)[0x7fc648180aa2] /usr/lib/x86_64-linux-gnu/libstdc++.so.6(_ZSt20__throw_out_of_rangePKc+0x67)[0x7fc6481d25d7] /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0xbe3d3)[0x7fc6481e03d3] ./Torchlight.bin.x86_64(_ZN11CFileSystem21buildMassiveDataGroupEv+0x453)[0x1617805] ./Torchlight.bin.x86_64(_ZN11CFileSystemC1Eb+0x14be)[0x16145ae] ./Torchlight.bin.x86_64(_ZN22CMasterResourceManagerC1EP9CSettings+0x41a)[0xfe1d0a] ./Torchlight.bin.x86_64(_ZN5CGame5setupEb+0x79a)[0x73ceaa] ./Torchlight.bin.x86_64(_ZN5CGame5beginEPv+0x28d)[0x73b839] ./Torchlight.bin.x86_64(main+0x649)[0x146dbe4] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf5)[0x7fc647861ec5] ./Torchlight.bin.x86_64[0x739ca9]

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  • Is throwing an error in unpredictable subclass-specific circumstances a violation of LSP?

    - by Motti Strom
    Say, I wanted to create a Java List<String> (see spec) implementation that uses a complex subsystem, such as a database or file system, for its store so that it becomes a simple persistent collection rather than an basic in-memory one. (We're limiting it specifically to a List of Strings for the purposes of discussion, but it could extended to automatically de-/serialise any object, with some help. We can also provide persistent Sets, Maps and so on in this way too.) So here's a skeleton implementation: class DbBackedList implements List<String> { private DbBackedList() {} /** Returns a list, possibly non-empty */ public static getList() { return new DbBackedList(); } public String get(int index) { return Db.getTable().getRow(i).asString(); // may throw DbExceptions! } // add(String), add(int, String), etc. ... } My problem lies with the fact that the underlying DB API may encounter connection errors that are not specified in the List interface that it should throw. My problem is whether this violates Liskov's Substitution Principle (LSP). Bob Martin actually gives an example of a PersistentSet in his paper on LSP that violates LSP. The difference is that his newly-specified Exception there is determined by the inserted value and so is strengthening the precondition. In my case the connection/read error is unpredictable and due to external factors and so is not technically a new precondition, merely an error of circumstance, perhaps like OutOfMemoryError which can occur even when unspecified. In normal circumstances, the new Error/Exception might never be thrown. (The caller could catch if it is aware of the possibility, just as a memory-restricted Java program might specifically catch OOME.) Is this therefore a valid argument for throwing an extra error and can I still claim to be a valid java.util.List (or pick your SDK/language/collection in general) and not in violation of LSP? If this does indeed violate LSP and thus not practically usable, I have provided two less-palatable alternative solutions as answers that you can comment on, see below. Footnote: Use Cases In the simplest case, the goal is to provide a familiar interface for cases when (say) a database is just being used as a persistent list, and allow regular List operations such as search, subList and iteration. Another, more adventurous, use-case is as a slot-in replacement for libraries that work with basic Lists, e.g if we have a third-party task queue that usually works with a plain List: new TaskWorkQueue(new ArrayList<String>()).start() which is susceptible to losing all it's queue in event of a crash, if we just replace this with: new TaskWorkQueue(new DbBackedList()).start() we get a instant persistence and the ability to share the tasks amongst more than one machine. In either case, we could either handle connection/read exceptions that are thrown, perhaps retrying the connection/read first, or allow them to throw and crash the program (e.g. if we can't change the TaskWorkQueue code).

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  • What are the differences between abstract classes, interfaces, and when to use them

    - by user66662
    Recently I have started to wrap my head around OOP, and I am now to the point where the more I read about the differences between Abstract classes and Interfaces the more confused I become. So far, neither can be instantiated. Interfaces are more or less structural blueprints that determine the skeleton and abstracts are different by being able to partially develop code. I would like to learn more about these through my specific situation. Here is a link to my first question if you would like a little more background information: What is a good design model for my new class? Here are two classes I created: class Ad { $title; $description $price; function get_data($website){ } function validate_price(){ } } class calendar_event { $title; $description $start_date; function get_data($website){ //guts } function validate_dates(){ //guts } } So, as you can see these classes are almost identical. Not shown here, but there are other functions, like get_zip(), save_to_database() that are common across my classes. I have also added other classes Cars and Pets which have all the common methods and of course properties specific to those objects (mileage, weight, for example). Now I have violated the DRY principle and I am managing and changing the same code across multiple files. I intend on having more classes like boats, horses, or whatever. So is this where I would use an interface or abstract class? From what I understand about abstract classes I would use a super class as a template with all of the common elements built into the abstract class, and then add only the items specifically needed in future classes. For example: abstract class content { $title; $description function get_data($website){ } function common_function2() { } function common_function3() { } } class calendar_event extends content { $start_date; function validate_dates(){ } } Or would I use an interface and, because these are so similar, create a structure that each of the subclasses are forced to use for integrity reasons, and leave it up to the end developer who fleshes out that class to be responsible for each of the details of even the common functions. my thinking there is that some 'common' functions may need to be tweaked in the future for the needs of their specific class. Despite all that above, if you believe I am misunderstanding the what and why of abstracts and interfaces altogether, by all means let a valid answer to be stop thinking in this direction and suggest the proper way to move forward! Thanks!

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  • Attempting to set up xampp and zend server on the same machine

    - by umbregachoong
    I am attempting to set up the zend server and xampp on the same machine but I am running into problems. I came across documentation on the zend site that said you cannot do this. However the folks over at apachefriends said you can. I have since discovered that I can run some of the zendframework examples within xampp by downloading the zendframework2 library and the skeleton app from git and I am doing this right now. However, I would like to know how to set them both up without having any conflicts both for the apache2 server and phpmyadmin. (One of the frustrating things is trying to load phpmyadmin in the deployment dialog by using the zpk tool in Zend). What I did in trying to set up both servers on windows 7 is as follows: First I have tried to set up the httpd conf files separately for each server, xampp running on port 8082 , and zend running on port 8088. At the time xampp would work, but zend server would not. This is after setting up the virtual host files separately for each server. Question 1: Where are the zend server error logs? Earlier, I was able to get both of them running configuring the xampp server httpd-conf file alone, however, I experienced problems with phpmyadmin even after configuring phpmyadmin on xampp to work on a different port other than 3306. Second question here: how to set up the two mysql phpmyadmin instances so they do not conflict with each other? Here is the xampp virtual host section: ##ServerAdmin [email protected] DocumentRoot "C:/xampp/htdocs/" ServerName localhost 8082 ##ServerAlias www.dummy-host.example.com ##ErrorLog "logs/dummy-host.example.com-error.log" ##CustomLog "logs/dummy-host.example.com-access.log" common Here is the zend virtual host section: DocumentRoot "C:\Program Files (x86)\Zend\Apache2/htdocs" ServerName localhost:8088 </VirtualHost> I have looked at this httpd.apache.org/docs/2.2/vhosts/ and this http://survivethedeepend.com/zendframeworkbook/en/1.0/creating.a.local.domain.using.apache.virtual.hosts but I am obviously doing something wrong here. I also have the java sdk running on this machine with tomcat and apache and I have no conflicts- too bad this is not the case for zend server and xampp Thanks umbre gachoong

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  • Upstart Script on Centos 6

    - by MarcusMaximus
    I'm trying to create an upstart script to run a python script on startup. In theory it looks simple enough but I just can't seem to get it to work. I'm using a skeleton script I found here and altered. description "Used to start python script as a service" author "Me <[email protected]>" # Stanzas # # Stanzas control when and how a process is started and stopped # See a list of stanzas here: http://upstart.ubuntu.com/wiki/Stanzas#respawn # When to start the service start on runlevel [2345] # When to stop the service stop on runlevel [016] # Automatically restart process if crashed respawn # Essentially lets upstart know the process will detach itself to the background expect fork # Start the process script exec su nonrootuser -c "python /usr/local/scripts/script.py" end script The test script I want it to run is currently a simple python script that runs without any issue when run from a terminal. #!/usr/bin/python2 import os, sys, time if __name__ == "__main__": for i in range (10000): message = "shotgunUpstartTest " , i , time.asctime() , " - Username: " , os.getenv("USERNAME") #print message time.sleep(60) out = open("/var/log/scripts/scriptlogfile", "a") print >> out, message out.close() The location/var/log/scripts has permissions 777 The file /usr/local/scripts/script.py has permissions 775 The upstart script /etc/init.d/pythonupstart.conf has permissions 755

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  • Run Python script at startup using upstart

    - by MarcusMaximus
    I'm trying to create an upstart script to run a python script on startup. In theory it looks simple enough but I just can't seem to get it to work. I'm using a skeleton script I found here and altered. description "Used to start python script as a service" author "Me <[email protected]>" # Stanzas # # Stanzas control when and how a process is started and stopped # See a list of stanzas here: http://upstart.ubuntu.com/wiki/Stanzas#respawn # When to start the service start on runlevel [2345] # When to stop the service stop on runlevel [016] # Automatically restart process if crashed respawn # Essentially lets upstart know the process will detach itself to the background expect fork # Start the process script exec python /usr/local/scripts/script.py end script The test script I want it to run is currently a simple python script that runs without any issue when run from a terminal. #!/usr/bin/python2 import os, sys, time if __name__ == "__main__": for i in range (10000): message = "UpstartTest " , i , time.asctime() , " - Username: " , os.getenv("USERNAME") #print message time.sleep(60) out = open("/var/log/scripts/scriptlogfile", "a") print >> out, message out.close() The location/var/log/scripts has permissions 777 The file /usr/local/scripts/script.py has permissions 775 The upstart script /etc/init.d/pythonupstart.conf has permissions 755

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  • A way of doing real-world test-driven development (and some thoughts about it)

    - by Thomas Weller
    Lately, I exchanged some arguments with Derick Bailey about some details of the red-green-refactor cycle of the Test-driven development process. In short, the issue revolved around the fact that it’s not enough to have a test red or green, but it’s also important to have it red or green for the right reasons. While for me, it’s sufficient to initially have a NotImplementedException in place, Derick argues that this is not totally correct (see these two posts: Red/Green/Refactor, For The Right Reasons and Red For The Right Reason: Fail By Assertion, Not By Anything Else). And he’s right. But on the other hand, I had no idea how his insights could have any practical consequence for my own individual interpretation of the red-green-refactor cycle (which is not really red-green-refactor, at least not in its pure sense, see the rest of this article). This made me think deeply for some days now. In the end I found out that the ‘right reason’ changes in my understanding depending on what development phase I’m in. To make this clear (at least I hope it becomes clear…) I started to describe my way of working in some detail, and then something strange happened: The scope of the article slightly shifted from focusing ‘only’ on the ‘right reason’ issue to something more general, which you might describe as something like  'Doing real-world TDD in .NET , with massive use of third-party add-ins’. This is because I feel that there is a more general statement about Test-driven development to make:  It’s high time to speak about the ‘How’ of TDD, not always only the ‘Why’. Much has been said about this, and me myself also contributed to that (see here: TDD is not about testing, it's about how we develop software). But always justifying what you do is very unsatisfying in the long run, it is inherently defensive, and it costs time and effort that could be used for better and more important things. And frankly: I’m somewhat sick and tired of repeating time and again that the test-driven way of software development is highly preferable for many reasons - I don’t want to spent my time exclusively on stating the obvious… So, again, let’s say it clearly: TDD is programming, and programming is TDD. Other ways of programming (code-first, sometimes called cowboy-coding) are exceptional and need justification. – I know that there are many people out there who will disagree with this radical statement, and I also know that it’s not a description of the real world but more of a mission statement or something. But nevertheless I’m absolutely sure that in some years this statement will be nothing but a platitude. Side note: Some parts of this post read as if I were paid by Jetbrains (the manufacturer of the ReSharper add-in – R#), but I swear I’m not. Rather I think that Visual Studio is just not production-complete without it, and I wouldn’t even consider to do professional work without having this add-in installed... The three parts of a software component Before I go into some details, I first should describe my understanding of what belongs to a software component (assembly, type, or method) during the production process (i.e. the coding phase). Roughly, I come up with the three parts shown below:   First, we need to have some initial sort of requirement. This can be a multi-page formal document, a vague idea in some programmer’s brain of what might be needed, or anything in between. In either way, there has to be some sort of requirement, be it explicit or not. – At the C# micro-level, the best way that I found to formulate that is to define interfaces for just about everything, even for internal classes, and to provide them with exhaustive xml comments. The next step then is to re-formulate these requirements in an executable form. This is specific to the respective programming language. - For C#/.NET, the Gallio framework (which includes MbUnit) in conjunction with the ReSharper add-in for Visual Studio is my toolset of choice. The third part then finally is the production code itself. It’s development is entirely driven by the requirements and their executable formulation. This is the delivery, the two other parts are ‘only’ there to make its production possible, to give it a decent quality and reliability, and to significantly reduce related costs down the maintenance timeline. So while the first two parts are not really relevant for the customer, they are very important for the developer. The customer (or in Scrum terms: the Product Owner) is not interested at all in how  the product is developed, he is only interested in the fact that it is developed as cost-effective as possible, and that it meets his functional and non-functional requirements. The rest is solely a matter of the developer’s craftsmanship, and this is what I want to talk about during the remainder of this article… An example To demonstrate my way of doing real-world TDD, I decided to show the development of a (very) simple Calculator component. The example is deliberately trivial and silly, as examples always are. I am totally aware of the fact that real life is never that simple, but I only want to show some development principles here… The requirement As already said above, I start with writing down some words on the initial requirement, and I normally use interfaces for that, even for internal classes - the typical question “intf or not” doesn’t even come to mind. I need them for my usual workflow and using them automatically produces high componentized and testable code anyway. To think about their usage in every single situation would slow down the production process unnecessarily. So this is what I begin with: namespace Calculator {     /// <summary>     /// Defines a very simple calculator component for demo purposes.     /// </summary>     public interface ICalculator     {         /// <summary>         /// Gets the result of the last successful operation.         /// </summary>         /// <value>The last result.</value>         /// <remarks>         /// Will be <see langword="null" /> before the first successful operation.         /// </remarks>         double? LastResult { get; }       } // interface ICalculator   } // namespace Calculator So, I’m not beginning with a test, but with a sort of code declaration - and still I insist on being 100% test-driven. There are three important things here: Starting this way gives me a method signature, which allows to use IntelliSense and AutoCompletion and thus eliminates the danger of typos - one of the most regular, annoying, time-consuming, and therefore expensive sources of error in the development process. In my understanding, the interface definition as a whole is more of a readable requirement document and technical documentation than anything else. So this is at least as much about documentation than about coding. The documentation must completely describe the behavior of the documented element. I normally use an IoC container or some sort of self-written provider-like model in my architecture. In either case, I need my components defined via service interfaces anyway. - I will use the LinFu IoC framework here, for no other reason as that is is very simple to use. The ‘Red’ (pt. 1)   First I create a folder for the project’s third-party libraries and put the LinFu.Core dll there. Then I set up a test project (via a Gallio project template), and add references to the Calculator project and the LinFu dll. Finally I’m ready to write the first test, which will look like the following: namespace Calculator.Test {     [TestFixture]     public class CalculatorTest     {         private readonly ServiceContainer container = new ServiceContainer();           [Test]         public void CalculatorLastResultIsInitiallyNull()         {             ICalculator calculator = container.GetService<ICalculator>();               Assert.IsNull(calculator.LastResult);         }       } // class CalculatorTest   } // namespace Calculator.Test       This is basically the executable formulation of what the interface definition states (part of). Side note: There’s one principle of TDD that is just plain wrong in my eyes: I’m talking about the Red is 'does not compile' thing. How could a compiler error ever be interpreted as a valid test outcome? I never understood that, it just makes no sense to me. (Or, in Derick’s terms: this reason is as wrong as a reason ever could be…) A compiler error tells me: Your code is incorrect, but nothing more.  Instead, the ‘Red’ part of the red-green-refactor cycle has a clearly defined meaning to me: It means that the test works as intended and fails only if its assumptions are not met for some reason. Back to our Calculator. When I execute the above test with R#, the Gallio plugin will give me this output: So this tells me that the test is red for the wrong reason: There’s no implementation that the IoC-container could load, of course. So let’s fix that. With R#, this is very easy: First, create an ICalculator - derived type:        Next, implement the interface members: And finally, move the new class to its own file: So far my ‘work’ was six mouse clicks long, the only thing that’s left to do manually here, is to add the Ioc-specific wiring-declaration and also to make the respective class non-public, which I regularly do to force my components to communicate exclusively via interfaces: This is what my Calculator class looks like as of now: using System; using LinFu.IoC.Configuration;   namespace Calculator {     [Implements(typeof(ICalculator))]     internal class Calculator : ICalculator     {         public double? LastResult         {             get             {                 throw new NotImplementedException();             }         }     } } Back to the test fixture, we have to put our IoC container to work: [TestFixture] public class CalculatorTest {     #region Fields       private readonly ServiceContainer container = new ServiceContainer();       #endregion // Fields       #region Setup/TearDown       [FixtureSetUp]     public void FixtureSetUp()     {        container.LoadFrom(AppDomain.CurrentDomain.BaseDirectory, "Calculator.dll");     }       ... Because I have a R# live template defined for the setup/teardown method skeleton as well, the only manual coding here again is the IoC-specific stuff: two lines, not more… The ‘Red’ (pt. 2) Now, the execution of the above test gives the following result: This time, the test outcome tells me that the method under test is called. And this is the point, where Derick and I seem to have somewhat different views on the subject: Of course, the test still is worthless regarding the red/green outcome (or: it’s still red for the wrong reasons, in that it gives a false negative). But as far as I am concerned, I’m not really interested in the test outcome at this point of the red-green-refactor cycle. Rather, I only want to assert that my test actually calls the right method. If that’s the case, I will happily go on to the ‘Green’ part… The ‘Green’ Making the test green is quite trivial. Just make LastResult an automatic property:     [Implements(typeof(ICalculator))]     internal class Calculator : ICalculator     {         public double? LastResult { get; private set; }     }         One more round… Now on to something slightly more demanding (cough…). Let’s state that our Calculator exposes an Add() method:         ...   /// <summary>         /// Adds the specified operands.         /// </summary>         /// <param name="operand1">The operand1.</param>         /// <param name="operand2">The operand2.</param>         /// <returns>The result of the additon.</returns>         /// <exception cref="ArgumentException">         /// Argument <paramref name="operand1"/> is &lt; 0.<br/>         /// -- or --<br/>         /// Argument <paramref name="operand2"/> is &lt; 0.         /// </exception>         double Add(double operand1, double operand2);       } // interface ICalculator A remark: I sometimes hear the complaint that xml comment stuff like the above is hard to read. That’s certainly true, but irrelevant to me, because I read xml code comments with the CR_Documentor tool window. And using that, it looks like this:   Apart from that, I’m heavily using xml code comments (see e.g. here for a detailed guide) because there is the possibility of automating help generation with nightly CI builds (using MS Sandcastle and the Sandcastle Help File Builder), and then publishing the results to some intranet location.  This way, a team always has first class, up-to-date technical documentation at hand about the current codebase. (And, also very important for speeding up things and avoiding typos: You have IntelliSense/AutoCompletion and R# support, and the comments are subject to compiler checking…).     Back to our Calculator again: Two more R# – clicks implement the Add() skeleton:         ...           public double Add(double operand1, double operand2)         {             throw new NotImplementedException();         }       } // class Calculator As we have stated in the interface definition (which actually serves as our requirement document!), the operands are not allowed to be negative. So let’s start implementing that. Here’s the test: [Test] [Row(-0.5, 2)] public void AddThrowsOnNegativeOperands(double operand1, double operand2) {     ICalculator calculator = container.GetService<ICalculator>();       Assert.Throws<ArgumentException>(() => calculator.Add(operand1, operand2)); } As you can see, I’m using a data-driven unit test method here, mainly for these two reasons: Because I know that I will have to do the same test for the second operand in a few seconds, I save myself from implementing another test method for this purpose. Rather, I only will have to add another Row attribute to the existing one. From the test report below, you can see that the argument values are explicitly printed out. This can be a valuable documentation feature even when everything is green: One can quickly review what values were tested exactly - the complete Gallio HTML-report (as it will be produced by the Continuous Integration runs) shows these values in a quite clear format (see below for an example). Back to our Calculator development again, this is what the test result tells us at the moment: So we’re red again, because there is not yet an implementation… Next we go on and implement the necessary parameter verification to become green again, and then we do the same thing for the second operand. To make a long story short, here’s the test and the method implementation at the end of the second cycle: // in CalculatorTest:   [Test] [Row(-0.5, 2)] [Row(295, -123)] public void AddThrowsOnNegativeOperands(double operand1, double operand2) {     ICalculator calculator = container.GetService<ICalculator>();       Assert.Throws<ArgumentException>(() => calculator.Add(operand1, operand2)); }   // in Calculator: public double Add(double operand1, double operand2) {     if (operand1 < 0.0)     {         throw new ArgumentException("Value must not be negative.", "operand1");     }     if (operand2 < 0.0)     {         throw new ArgumentException("Value must not be negative.", "operand2");     }     throw new NotImplementedException(); } So far, we have sheltered our method from unwanted input, and now we can safely operate on the parameters without further caring about their validity (this is my interpretation of the Fail Fast principle, which is regarded here in more detail). Now we can think about the method’s successful outcomes. First let’s write another test for that: [Test] [Row(1, 1, 2)] public void TestAdd(double operand1, double operand2, double expectedResult) {     ICalculator calculator = container.GetService<ICalculator>();       double result = calculator.Add(operand1, operand2);       Assert.AreEqual(expectedResult, result); } Again, I’m regularly using row based test methods for these kinds of unit tests. The above shown pattern proved to be extremely helpful for my development work, I call it the Defined-Input/Expected-Output test idiom: You define your input arguments together with the expected method result. There are two major benefits from that way of testing: In the course of refining a method, it’s very likely to come up with additional test cases. In our case, we might add tests for some edge cases like ‘one of the operands is zero’ or ‘the sum of the two operands causes an overflow’, or maybe there’s an external test protocol that has to be fulfilled (e.g. an ISO norm for medical software), and this results in the need of testing against additional values. In all these scenarios we only have to add another Row attribute to the test. Remember that the argument values are written to the test report, so as a side-effect this produces valuable documentation. (This can become especially important if the fulfillment of some sort of external requirements has to be proven). So your test method might look something like that in the end: [Test, Description("Arguments: operand1, operand2, expectedResult")] [Row(1, 1, 2)] [Row(0, 999999999, 999999999)] [Row(0, 0, 0)] [Row(0, double.MaxValue, double.MaxValue)] [Row(4, double.MaxValue - 2.5, double.MaxValue)] public void TestAdd(double operand1, double operand2, double expectedResult) {     ICalculator calculator = container.GetService<ICalculator>();       double result = calculator.Add(operand1, operand2);       Assert.AreEqual(expectedResult, result); } And this will produce the following HTML report (with Gallio):   Not bad for the amount of work we invested in it, huh? - There might be scenarios where reports like that can be useful for demonstration purposes during a Scrum sprint review… The last requirement to fulfill is that the LastResult property is expected to store the result of the last operation. I don’t show this here, it’s trivial enough and brings nothing new… And finally: Refactor (for the right reasons) To demonstrate my way of going through the refactoring portion of the red-green-refactor cycle, I added another method to our Calculator component, namely Subtract(). Here’s the code (tests and production): // CalculatorTest.cs:   [Test, Description("Arguments: operand1, operand2, expectedResult")] [Row(1, 1, 0)] [Row(0, 999999999, -999999999)] [Row(0, 0, 0)] [Row(0, double.MaxValue, -double.MaxValue)] [Row(4, double.MaxValue - 2.5, -double.MaxValue)] public void TestSubtract(double operand1, double operand2, double expectedResult) {     ICalculator calculator = container.GetService<ICalculator>();       double result = calculator.Subtract(operand1, operand2);       Assert.AreEqual(expectedResult, result); }   [Test, Description("Arguments: operand1, operand2, expectedResult")] [Row(1, 1, 0)] [Row(0, 999999999, -999999999)] [Row(0, 0, 0)] [Row(0, double.MaxValue, -double.MaxValue)] [Row(4, double.MaxValue - 2.5, -double.MaxValue)] public void TestSubtractGivesExpectedLastResult(double operand1, double operand2, double expectedResult) {     ICalculator calculator = container.GetService<ICalculator>();       calculator.Subtract(operand1, operand2);       Assert.AreEqual(expectedResult, calculator.LastResult); }   ...   // ICalculator.cs: /// <summary> /// Subtracts the specified operands. /// </summary> /// <param name="operand1">The operand1.</param> /// <param name="operand2">The operand2.</param> /// <returns>The result of the subtraction.</returns> /// <exception cref="ArgumentException"> /// Argument <paramref name="operand1"/> is &lt; 0.<br/> /// -- or --<br/> /// Argument <paramref name="operand2"/> is &lt; 0. /// </exception> double Subtract(double operand1, double operand2);   ...   // Calculator.cs:   public double Subtract(double operand1, double operand2) {     if (operand1 < 0.0)     {         throw new ArgumentException("Value must not be negative.", "operand1");     }       if (operand2 < 0.0)     {         throw new ArgumentException("Value must not be negative.", "operand2");     }       return (this.LastResult = operand1 - operand2).Value; }   Obviously, the argument validation stuff that was produced during the red-green part of our cycle duplicates the code from the previous Add() method. So, to avoid code duplication and minimize the number of code lines of the production code, we do an Extract Method refactoring. One more time, this is only a matter of a few mouse clicks (and giving the new method a name) with R#: Having done that, our production code finally looks like that: using System; using LinFu.IoC.Configuration;   namespace Calculator {     [Implements(typeof(ICalculator))]     internal class Calculator : ICalculator     {         #region ICalculator           public double? LastResult { get; private set; }           public double Add(double operand1, double operand2)         {             ThrowIfOneOperandIsInvalid(operand1, operand2);               return (this.LastResult = operand1 + operand2).Value;         }           public double Subtract(double operand1, double operand2)         {             ThrowIfOneOperandIsInvalid(operand1, operand2);               return (this.LastResult = operand1 - operand2).Value;         }           #endregion // ICalculator           #region Implementation (Helper)           private static void ThrowIfOneOperandIsInvalid(double operand1, double operand2)         {             if (operand1 < 0.0)             {                 throw new ArgumentException("Value must not be negative.", "operand1");             }               if (operand2 < 0.0)             {                 throw new ArgumentException("Value must not be negative.", "operand2");             }         }           #endregion // Implementation (Helper)       } // class Calculator   } // namespace Calculator But is the above worth the effort at all? It’s obviously trivial and not very impressive. All our tests were green (for the right reasons), and refactoring the code did not change anything. It’s not immediately clear how this refactoring work adds value to the project. Derick puts it like this: STOP! Hold on a second… before you go any further and before you even think about refactoring what you just wrote to make your test pass, you need to understand something: if your done with your requirements after making the test green, you are not required to refactor the code. I know… I’m speaking heresy, here. Toss me to the wolves, I’ve gone over to the dark side! Seriously, though… if your test is passing for the right reasons, and you do not need to write any test or any more code for you class at this point, what value does refactoring add? Derick immediately answers his own question: So why should you follow the refactor portion of red/green/refactor? When you have added code that makes the system less readable, less understandable, less expressive of the domain or concern’s intentions, less architecturally sound, less DRY, etc, then you should refactor it. I couldn’t state it more precise. From my personal perspective, I’d add the following: You have to keep in mind that real-world software systems are usually quite large and there are dozens or even hundreds of occasions where micro-refactorings like the above can be applied. It’s the sum of them all that counts. And to have a good overall quality of the system (e.g. in terms of the Code Duplication Percentage metric) you have to be pedantic on the individual, seemingly trivial cases. My job regularly requires the reading and understanding of ‘foreign’ code. So code quality/readability really makes a HUGE difference for me – sometimes it can be even the difference between project success and failure… Conclusions The above described development process emerged over the years, and there were mainly two things that guided its evolution (you might call it eternal principles, personal beliefs, or anything in between): Test-driven development is the normal, natural way of writing software, code-first is exceptional. So ‘doing TDD or not’ is not a question. And good, stable code can only reliably be produced by doing TDD (yes, I know: many will strongly disagree here again, but I’ve never seen high-quality code – and high-quality code is code that stood the test of time and causes low maintenance costs – that was produced code-first…) It’s the production code that pays our bills in the end. (Though I have seen customers these days who demand an acceptance test battery as part of the final delivery. Things seem to go into the right direction…). The test code serves ‘only’ to make the production code work. But it’s the number of delivered features which solely counts at the end of the day - no matter how much test code you wrote or how good it is. With these two things in mind, I tried to optimize my coding process for coding speed – or, in business terms: productivity - without sacrificing the principles of TDD (more than I’d do either way…).  As a result, I consider a ratio of about 3-5/1 for test code vs. production code as normal and desirable. In other words: roughly 60-80% of my code is test code (This might sound heavy, but that is mainly due to the fact that software development standards only begin to evolve. The entire software development profession is very young, historically seen; only at the very beginning, and there are no viable standards yet. If you think about software development as a kind of casting process, where the test code is the mold and the resulting production code is the final product, then the above ratio sounds no longer extraordinary…) Although the above might look like very much unnecessary work at first sight, it’s not. With the aid of the mentioned add-ins, doing all the above is a matter of minutes, sometimes seconds (while writing this post took hours and days…). The most important thing is to have the right tools at hand. Slow developer machines or the lack of a tool or something like that - for ‘saving’ a few 100 bucks -  is just not acceptable and a very bad decision in business terms (though I quite some times have seen and heard that…). Production of high-quality products needs the usage of high-quality tools. This is a platitude that every craftsman knows… The here described round-trip will take me about five to ten minutes in my real-world development practice. I guess it’s about 30% more time compared to developing the ‘traditional’ (code-first) way. But the so manufactured ‘product’ is of much higher quality and massively reduces maintenance costs, which is by far the single biggest cost factor, as I showed in this previous post: It's the maintenance, stupid! (or: Something is rotten in developerland.). In the end, this is a highly cost-effective way of software development… But on the other hand, there clearly is a trade-off here: coding speed vs. code quality/later maintenance costs. The here described development method might be a perfect fit for the overwhelming majority of software projects, but there certainly are some scenarios where it’s not - e.g. if time-to-market is crucial for a software project. So this is a business decision in the end. It’s just that you have to know what you’re doing and what consequences this might have… Some last words First, I’d like to thank Derick Bailey again. His two aforementioned posts (which I strongly recommend for reading) inspired me to think deeply about my own personal way of doing TDD and to clarify my thoughts about it. I wouldn’t have done that without this inspiration. I really enjoy that kind of discussions… I agree with him in all respects. But I don’t know (yet?) how to bring his insights into the described production process without slowing things down. The above described method proved to be very “good enough” in my practical experience. But of course, I’m open to suggestions here… My rationale for now is: If the test is initially red during the red-green-refactor cycle, the ‘right reason’ is: it actually calls the right method, but this method is not yet operational. Later on, when the cycle is finished and the tests become part of the regular, automated Continuous Integration process, ‘red’ certainly must occur for the ‘right reason’: in this phase, ‘red’ MUST mean nothing but an unfulfilled assertion - Fail By Assertion, Not By Anything Else!

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  • Talking JavaOne with Rock Star Simon Ritter

    - by Janice J. Heiss
    Oracle’s Java Technology Evangelist Simon Ritter is well known at JavaOne for his quirky and fun-loving sessions, which, this year include: CON4644 -- “JavaFX Extreme GUI Makeover” (with Angela Caicedo on how to improve UIs in JavaFX) CON5352 -- “Building JavaFX Interfaces for the Real World” (Kinect gesture tracking and mind reading) CON5348 -- “Do You Like Coffee with Your Dessert?” (Some cool demos of Java of the Raspberry Pi) CON6375 -- “Custom JavaFX Charts: (How to extend JavaFX Chart controls with some interesting things) I recently asked Ritter about the significance of the Raspberry Pi, the topic of one of his sessions that consists of a credit card-sized single-board computer developed in the UK with the intention of stimulating the teaching of basic computer science in schools. “I don't think there's one definitive thing that makes the RP significant,” observed Ritter, “but a combination of things that really makes it stand out. First, it's the cost: $35 for what is effectively a completely usable computer. OK, so you have to add a power supply, SD card for storage and maybe a screen, keyboard and mouse, but this is still way cheaper than a typical PC. The choice of an ARM processor is also significant, as it avoids problems like cooling (no heat sink or fan) and can use a USB power brick.  Combine these two things with the immense groundswell of community support and it provides a fantastic platform for teaching young and old alike about computing, which is the real goal of the project.”He informed me that he’ll be at the Raspberry Pi meetup on Saturday (not part of JavaOne). Check out the details here.JavaFX InterfacesWhen I asked about how JavaFX can interface with the real world, he said that there are many ways. “JavaFX provides you with a simple set of programming interfaces that can create complex, cool and compelling user interfaces,” explained Ritter. “Because it's just Java code you can combine JavaFX with any other Java library to provide data to display and control the interface. What I've done for my session is look at some of the possible ways of doing this using some of the amazing hardware that's available today at very low cost. The Kinect sensor has added a new dimension to gaming in terms of interaction; there's a Java API to access this so you can easily collect skeleton tracking data from it. Some clever people have also written libraries that can track gestures like swipes, circles, pushes, and so on. We use these to control parts of the UI. I've also experimented with a Neurosky EEG sensor that can in some ways ‘read your mind’ (well, at least measure some of the brain functions like attention and meditation).  I've written a Java library for this that I include as a way of controlling the UI. We're not quite at the stage of just thinking a command though!” Here Comes Java EmbeddedAnd what, from Ritter’s perspective, is the most exciting thing happening in the world of Java today? “I think it's seeing just how Java continues to become more and more pervasive,” he said. “One of the areas that is growing rapidly is embedded systems.  We've talked about the ‘Internet of things’ for many years; now it's finally becoming a reality. With the ability of more and more devices to include processing, storage and networking we need an easy way to write code for them that's reliable, has high performance, and is secure. Java fits all these requirements. With Java Embedded being a conference within a conference, I'm very excited about the possibilities of Java in this space.”Check out Ritter’s sessions or say hi if you run into him. Originally published on blogs.oracle.com/javaone.

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  • Talking JavaOne with Rock Star Simon Ritter

    - by Janice J. Heiss
    Oracle’s Java Technology Evangelist Simon Ritter is well known at JavaOne for his quirky and fun-loving sessions, which, this year include: CON4644 -- “JavaFX Extreme GUI Makeover” (with Angela Caicedo on how to improve UIs in JavaFX) CON5352 -- “Building JavaFX Interfaces for the Real World” (Kinect gesture tracking and mind reading) CON5348 -- “Do You Like Coffee with Your Dessert?” (Some cool demos of Java of the Raspberry Pi) CON6375 -- “Custom JavaFX Charts: (How to extend JavaFX Chart controls with some interesting things) I recently asked Ritter about the significance of the Raspberry Pi, the topic of one of his sessions that consists of a credit card-sized single-board computer developed in the UK with the intention of stimulating the teaching of basic computer science in schools. “I don't think there's one definitive thing that makes the RP significant,” observed Ritter, “but a combination of things that really makes it stand out. First, it's the cost: $35 for what is effectively a completely usable computer. OK, so you have to add a power supply, SD card for storage and maybe a screen, keyboard and mouse, but this is still way cheaper than a typical PC. The choice of an ARM processor is also significant, as it avoids problems like cooling (no heat sink or fan) and can use a USB power brick.  Combine these two things with the immense groundswell of community support and it provides a fantastic platform for teaching young and old alike about computing, which is the real goal of the project.”He informed me that he’ll be at the Raspberry Pi meetup on Saturday (not part of JavaOne). Check out the details here.JavaFX InterfacesWhen I asked about how JavaFX can interface with the real world, he said that there are many ways. “JavaFX provides you with a simple set of programming interfaces that can create complex, cool and compelling user interfaces,” explained Ritter. “Because it's just Java code you can combine JavaFX with any other Java library to provide data to display and control the interface. What I've done for my session is look at some of the possible ways of doing this using some of the amazing hardware that's available today at very low cost. The Kinect sensor has added a new dimension to gaming in terms of interaction; there's a Java API to access this so you can easily collect skeleton tracking data from it. Some clever people have also written libraries that can track gestures like swipes, circles, pushes, and so on. We use these to control parts of the UI. I've also experimented with a Neurosky EEG sensor that can in some ways ‘read your mind’ (well, at least measure some of the brain functions like attention and meditation).  I've written a Java library for this that I include as a way of controlling the UI. We're not quite at the stage of just thinking a command though!” Here Comes Java EmbeddedAnd what, from Ritter’s perspective, is the most exciting thing happening in the world of Java today? “I think it's seeing just how Java continues to become more and more pervasive,” he said. “One of the areas that is growing rapidly is embedded systems.  We've talked about the ‘Internet of things’ for many years; now it's finally becoming a reality. With the ability of more and more devices to include processing, storage and networking we need an easy way to write code for them that's reliable, has high performance, and is secure. Java fits all these requirements. With Java Embedded being a conference within a conference, I'm very excited about the possibilities of Java in this space.”Check out Ritter’s sessions or say hi if you run into him.

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  • BizTalk 2009 - Pipeline Component Wizard

    - by Stuart Brierley
    Recently I decided to try out the BizTalk Server Pipeline Component Wizard when creating a new pipeline component for BizTalk 2009. There are different versions of the wizard available, so be sure to download the appropriate version for the BizTalk environment that you are working with. Following the download and expansion of the zip file, you should be left with a Visual Studio solution.  Open this solution and build the project. Following this installation is straight foward - locate and run the built setup.exe file in the PipelineComponentWizard Setup project and click through the small number of installation screens. Once you have completed installation you will be ready to use the wizard in Visual Studio to create your BizTalk Pipeline Component. Start by creating a new project, selecting BizTalk Projects then BizTalk Server Pipeline Component.  You will then be presented with the splash screen. The next step is General Setup, where you will detail the classname, namespace, pipeline and component types, and the implementation language for your Pipeline Component. The options for pipeline type are Receive, Send or Any. Depending on the pipeline type chosen there are different options presented for the component type, matching those available within the BizTalk Pipelines themselves: Receive - Decoder, Disassembling Parser, Validate, Party Resolver, Any. Send -  Encoder, Assembling Serializer, Any. Any - Any. The options for implementation language are C# or VB.Net Next you must set up the UI settings - these are the settings that affect the appearance of the pipeline component within Visual Studio. You must detail the component name, version, description and icon.  Next is the definition of the variables that the pipeline component will use.  The values for these variables will be defined in Visual Studio when creating a pipeline. The options for each variable you require are: Designer Property - The name of the variable. Data Type - String, Boolean, Integer, Long, Short, Schema List, Schema With None Clicking finish now will complete the wizard stage of the creation of your pipeline component. Once the wizard has completed you will be left with a BizTalk Server Pipeline Component project containing a skeleton code file for you to complete.   Within this code file you will mainly be interested in the execute method, which is left mostly empty ready for you to implement your custom pipeline code:          #region IComponent members         /// <summary>         /// Implements IComponent.Execute method.         /// </summary>         /// <param name="pc">Pipeline context</param>         /// <param name="inmsg">Input message</param>         /// <returns>Original input message</returns>         /// <remarks>         /// IComponent.Execute method is used to initiate         /// the processing of the message in this pipeline component.         /// </remarks>         public Microsoft.BizTalk.Message.Interop.IBaseMessage Execute(Microsoft.BizTalk.Component.Interop.IPipelineContext pc, Microsoft.BizTalk.Message.Interop.IBaseMessage inmsg)         {             //             // TODO: implement component logic             //             // this way, it's a passthrough pipeline component             return inmsg;         }         #endregion Once you have implemented your custom code, build and compile your Custom Pipeline Component then add the compiled .dll to C:\Program Files\Microsoft BizTalk Server 2009\Pipeline Components . When creating a new pipeline, in Visual Studio reset the toolbox and the custom pipeline component should appear ready for you to use in your Biztalk Pipeline. Drop the pipeline component into the relevant pipeline stage and configure the component properties (the variables defined in the wizard). You can now deploy and use the pipeline as you would any other custom pipeline.

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  • My First Iteration Zero

    - by onefloridacoder
    I recently watched a web cast that covered the idea of planning from the concept stage to the product backlog.  It was the first content I had seen related to Iteration Zero and it made a lot of sense from a planning and engagement perspective where the customer is concerned.  It illuminated some of the problems I’ve experienced with getting a large project of the ground.  The idea behind this is to just figure out get everyone to understand what needs to be constructed and to build the initial feature set from a *very* high level.  Once that happens other parts of the high level construction start to take place.  You end up with a feature list that describes what the business wants the system to do, and what it potentially may (or may not) interact with.  Low tech tools are used to create UI mockups that can be used as a starting point for some of the key UI pieces. Toward the end of the webcast they speaker introduced something that was new to me.  He referred to it as an executable skeleton or the steel thread.  The idea with this part of the webcast was to describe walking through the different mocked layers of the application.  Not all layers and collaborators are involved at this stage since it’s Iteration Zero, and each layer is either hard-coded or completely mocked to provide a 35K foot view of how the different layers layers work together.  So imagine two actors on each side of a layer diagram and the flow goes down from the upper left side down through a a consumer, thorough a service layer and then back up the service layer to the destination/actor. I would imagine much could be discussed moving through new/planned or existing/legacy layers, or a little of both to see what’s implied by the current high-level design. One part of the web cast has the business and design team creating the product box (think of your favorite cereal or toy box) with all of the features and even pictures laid out on the outside of the box.  The notion here is that if you handed this box to someone and told them your system was inside they would have an understanding of what the system would be able to do, or the features it could provide.    One of the interesting parts of the webcast was where the speaker described that he worked with a couple of groups in the same room and each group came up with a different product box – the point is that each group had a different idea of what the system was supposed to do.  At this point of the project I thought that to be valuable considering my experience has been that historically this has taken longer than a week to realize that the business unit and design teams see the high level solution differently.  Once my box is finished I plan on moving to the next stage of solution definition which is to plan the UI for this small application using Excel, to map out the UI elements.  I’m my own customer so it feels like cheating, but taking these slow deliberate steps have already provided a few learning opportunities.    So I resist the urge to load all of my user stories into my newly installed VS2010  TFS project and try to reduce or add to, the number of user stories and/or refine the high level estimates I’ve come up with so far.

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  • When things go awry

    - by Phil Factor
    The moment the Entrepreneur opened his mouth on prime-time national TV, spelled out the URL and waxed big on how exciting ‘his’ new website was, I knew I was in for a busy night. I’d designed and built it. All at once, half a million people tried to log into the website. Although all my stress-testing paid off, I have to admit that the network locked up tight long before there was any danger of a database or website problem. Soon afterwards, the Entrepreneur and the Big Boss were there in the autopsy meeting. We picked through all our systems in detail to see how they’d borne the unexpected strain. Mercifully, in view of the sour mood of the Big Boss, it turned out that the only thing we could have done better was buy a bigger pipe to and from the internet. We’d specified that ‘big pipe’ when designing the system. The Big Boss had then railed at the cost and so we’d subsequently compromised. I felt that my design decisions were vindicated. The Big Boss brooded for a while. Then he made the significant comment: “What really ****** me off is the fact that, for ten minutes, we couldn’t take people’s money.” At that point I stopped feeling smug. Had the internet connection been better, the system would have reached its limit and failed rather precipitously, and that wasn’t what he wanted. Then it occurred to me that what had gummed up the connection was all those images on the site, that had made it so impressive for the visitors. If there had been a way to automatically pare down the site to the bare essentials under stress… Hmm. I began to consider disaster-recovery in the broadest sense – maintaining a service in spite of unusual or unexpected events. What he said makes a lot of sense: sacrifice whatever isn’t essential to keep the core service running when we approach the capacity limits. Maybe in IT we should borrow (or revive) the business concept of the ‘Skeleton service’, maintaining only the priority parts under stress, using a process that is well-prepared and carefully rehearsed. How might this work? Whatever the event we have to prepare for, it is all about understanding the priorities; knowing what one can dispense with when the going gets tough. In the event of database disaster, it’s much faster to deploy a skeletal system with only the essential data than to restore the entire system, though there would have to be a reconciliation process to update the revived database retrospectively, once the emergency was over. It isn’t just the database that could be designed for resilience. One could prepare for unusually high traffic in a website by designing a system that degraded gradually to a ‘skeletal’ site, one that maintained the commercial essentials without fat images, JavaScript libraries and razzmatazz. This is all what the Big Boss scathingly called ‘a mere technicality’. It seems to me that what is needed first is a culture of application and database design which acknowledges that we live in a very imperfect world, and react accordingly when things go awry.

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  • Validation and authorization in layered architecture

    - by SonOfPirate
    I know you are thinking (or maybe yelling), "not another question asking where validation belongs in a layered architecture?!?" Well, yes, but hopefully this will be a little bit of a different take on the subject. I am a firm believer that validation takes many forms, is context-based and varies at each level of the architecture. That is the basis for the post - helping to identify what type of validation should be performed in each layer. In addition, a question that often comes up is where authorization checks belong. The example scenario comes from an application for a catering business. Periodically during the day, a driver may turn in to the office any excess cash they've accumulated while taking the truck from site to site. The application allows a user to record the 'cash drop' by collecting the driver's ID, and the amount. Here's some skeleton code to illustrate the layers involved: public class CashDropApi // This is in the Service Facade Layer { [WebInvoke(Method = "POST")] public void AddCashDrop(NewCashDropContract contract) { // 1 Service.AddCashDrop(contract.Amount, contract.DriverId); } } public class CashDropService // This is the Application Service in the Domain Layer { public void AddCashDrop(Decimal amount, Int32 driverId) { // 2 CommandBus.Send(new AddCashDropCommand(amount, driverId)); } } internal class AddCashDropCommand // This is a command object in Domain Layer { public AddCashDropCommand(Decimal amount, Int32 driverId) { // 3 Amount = amount; DriverId = driverId; } public Decimal Amount { get; private set; } public Int32 DriverId { get; private set; } } internal class AddCashDropCommandHandler : IHandle<AddCashDropCommand> { internal ICashDropFactory Factory { get; set; } // Set by IoC container internal ICashDropRepository CashDrops { get; set; } // Set by IoC container internal IEmployeeRepository Employees { get; set; } // Set by IoC container public void Handle(AddCashDropCommand command) { // 4 var driver = Employees.GetById(command.DriverId); // 5 var authorizedBy = CurrentUser as Employee; // 6 var cashDrop = Factory.CreateCashDrop(command.Amount, driver, authorizedBy); // 7 CashDrops.Add(cashDrop); } } public class CashDropFactory { public CashDrop CreateCashDrop(Decimal amount, Employee driver, Employee authorizedBy) { // 8 return new CashDrop(amount, driver, authorizedBy, DateTime.Now); } } public class CashDrop // The domain object (entity) { public CashDrop(Decimal amount, Employee driver, Employee authorizedBy, DateTime at) { // 9 ... } } public class CashDropRepository // The implementation is in the Data Access Layer { public void Add(CashDrop item) { // 10 ... } } I've indicated 10 locations where I've seen validation checks placed in code. My question is what checks you would, if any, be performing at each given the following business rules (along with standard checks for length, range, format, type, etc): The amount of the cash drop must be greater than zero. The cash drop must have a valid Driver. The current user must be authorized to add cash drops (current user is not the driver). Please share your thoughts, how you have or would approach this scenario and the reasons for your choices.

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