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  • Trying to get DNS services running on Windows Server 2008 R2, what am I getting wrong ?

    - by LaserBeak
    Ok, So I am basically trying to get a home server pc up that will provide Domain name services, act as Mail server and web server. I have one static IP, well it's not officially static but hasn't changed in two years so I'll call it static. I have done the following: Configured router NAT/virtual port forward UDP/TCP port 53 to the internal IP of my server 192.168.1.16, in adapter settings specified the manual settings: 192.168.1.16 IP, gateway 192.168.1.1, Subnet: 255.255.255.0 and loopback DNS: 127.0.0.1 Using my public my public IP Checked using http://www.canyouseeme.org/ that port 53 is open and is not being blocked by my ISP. It can see services on this port. Registered Domain name (mydomain.com.au) Updated whois database through the domain registrars site and registered NameServer names: ns0.mydomain.com.au and ns2.mydomain.com.au, both have been associated with my single public IP. (Waited 24 hours) Update the nameserver for mydomain.com.au: primary ns0.mydomain.com.au secondary: ns2.mydomain.com.au (waited 24+ hours) Installed Server 2008 R2, install web server role and DNS role. Webserver works when I enter my public IP into browser of any PC/mobile, get IIS7 welcome page. In DNS server: Created new forward lookup zone: ; ; Database file mydoman.com.au.dns for mydomain.com.au zone. ; Zone version: 10 ; @ IN SOA mydomain.com.au. mydomain.testdomain.com. ( 10 ; serial number 900 ; refresh 600 ; retry 86400 ; expire 3600 ) ; default TTL ; ; Zone NS records ; @ NS ns0.mydomain.com.au. @ NS ns1.mydomain.com.au. ; ; Zone records ; @ A 192.168.1.16 www A 192.168.1.16 The Domain name services will however not work, the whois database updated with ns0.mydomain.com.au etc. but when I type in my site name www.mydomain.com.au from an external machine it will not open site and I can't even ping it (Can't find host) When I check the ns0.mydomain.com.au NS record using a tool Like: http://www.squish.net/dnscheck/ I get: Security: Server ns0.mydomain.com.au (XXX.XXX.XXX.XX <- my public IP) is recursive Domain exists but there is no such record Any ideas, thanks...

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  • a couple of questions about proxy server,vpn & how they works

    - by Q8Y
    I have a couple of questions that are related to security. Correct me if i'm wrong :) If I want to request something (ex: visiting www.google.com): my computer will request that then it will to the ISP then to my ISP proxy server that will take the request and act as a middle man in this situation ask for the site (www.google.com) and retrieve it then the proxy will send it back to me. I know that its being done like that. So, my question is that, in this situation my ISP knows everything and what I did request, and the proxy server is set by default (when I ask for an internet subscription). So, if I use here another proxy (lets assume that is a highly anonymous and my ISP can't detect my IP address from it), would I visit my ISP and then from my ISP it will redirect me to the new proxy server that I provide? Will it know that there is someone using another proxy? Or will it go to another network rather than my ISP? Because I didn't get the view clearly. This question is related to the first one. When I use a VPN, I know that VPN provides for me a tunneling, encryption and much more features that a proxy can't. So my data is travelling securely and my ISP can't know what I'm doing. But my questions are: From where is the tunneling started? Does it start after I visit the ISP network (since they are the one that are responsible for forwarding my data and requests)? If so, then not all my connection is tunneled in this way, there is a part that is not being tunneled. Since, every time I need to do anything I have to go to my ISP and ask to do that. Correct me if I misunderstand this. I know that VPN can let my computer be virtually in another place and access its resources (ex: be like in my office while I'm in my home. This is done via VPN). If I use a VPN service provider so that I can access the internet securely and without being monitored by my ISP. In this case, where is my encrypted data saved? Is it saved in my ISP or in the VPN service provider? If I use a VPN, does anyone on the internet know what I'm doing or who I am? Even the VPN service provider? Can they know me? I think they should know the person that is asking for this VPN service, am I right?

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  • Unit Testing - Am I doing it right?

    - by baron
    Hi everyone, Basically I have been programing for a little while and after finishing my last project can fully understand how much easier it would have been if I'd have done TDD. I guess I'm still not doing it strictly as I am still writing code then writing a test for it, I don't quite get how the test becomes before the code if you don't know what structures and how your storing data etc... but anyway... Kind of hard to explain but basically lets say for example I have a Fruit objects with properties like id, color and cost. (All stored in textfile ignore completely any database logic etc) FruitID FruitName FruitColor FruitCost 1 Apple Red 1.2 2 Apple Green 1.4 3 Apple HalfHalf 1.5 This is all just for example. But lets say I have this is a collection of Fruit (it's a List<Fruit>) objects in this structure. And my logic will say to reorder the fruitids in the collection if a fruit is deleted (this is just how the solution needs to be). E.g. if 1 is deleted, object 2 takes fruit id 1, object 3 takes fruit id2. Now I want to test the code ive written which does the reordering, etc. How can I set this up to do the test? Here is where I've got so far. Basically I have fruitManager class with all the methods, like deletefruit, etc. It has the list usually but Ive changed hte method to test it so that it accepts a list, and the info on the fruit to delete, then returns the list. Unit-testing wise: Am I basically doing this the right way, or have I got the wrong idea? and then I test deleting different valued objects / datasets to ensure method is working properly. [Test] public void DeleteFruit() { var fruitList = CreateFruitList(); var fm = new FruitManager(); var resultList = fm.DeleteFruitTest("Apple", 2, fruitList); //Assert that fruitobject with x properties is not in list ? how } private static List<Fruit> CreateFruitList() { //Build test data var f01 = new Fruit {Name = "Apple",Id = 1, etc...}; var f02 = new Fruit {Name = "Apple",Id = 2, etc...}; var f03 = new Fruit {Name = "Apple",Id = 3, etc...}; var fruitList = new List<Fruit> {f01, f02, f03}; return fruitList; }

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  • C++ string sort like a human being?

    - by Walter Nissen
    I would like to sort alphanumeric strings the way a human being would sort them. I.e., "A2" comes before "A10", and "a" certainly comes before "Z"! Is there any way to do with without writing a mini-parser? Ideally it would also put "A1B1" before "A1B10". I see the question "Natural (human alpha-numeric) sort in Microsoft SQL 2005" with a possible answer, but it uses various library functions, as does "Sorting Strings for Humans with IComparer". Below is a test case that currently fails: #include <set> #include <iterator> #include <iostream> #include <vector> #include <cassert> template <typename T> struct LexicographicSort { inline bool operator() (const T& lhs, const T& rhs) const{ std::ostringstream s1,s2; s1 << toLower(lhs); s2 << toLower(rhs); bool less = s1.str() < s2.str(); std::cout<<s1.str()<<" "<<s2.str()<<" "<<less<<"\n"; return less; } inline std::string toLower(const std::string& str) const { std::string newString(""); for (std::string::const_iterator charIt = str.begin(); charIt!=str.end();++charIt) { newString.push_back(std::tolower(*charIt)); } return newString; } }; int main(void) { const std::string reference[5] = {"ab","B","c1","c2","c10"}; std::vector<std::string> referenceStrings(&(reference[0]), &(reference[5])); //Insert in reverse order so we know they get sorted std::set<std::string,LexicographicSort<std::string> > strings(referenceStrings.rbegin(), referenceStrings.rend()); std::cout<<"Items:\n"; std::copy(strings.begin(), strings.end(), std::ostream_iterator<std::string>(std::cout, "\n")); std::vector<std::string> sortedStrings(strings.begin(), strings.end()); assert(sortedStrings == referenceStrings); }

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  • What is the probable failure - no BSOD, no event log, monitors sleeping, force reboot required

    - by Tyler
    Every 3 to 15 days, my PC freezes. This typically happens when the computer is idle, I'm coming home from work, back from vacation, etc. It's never happened while using my computer. The monitors are in power save mode The Caps Lock light on the (wireless) keyboard doesn't work Ctrl-alt-del has no effect, mouse (wireless) has no effect The hardware reset button and single press of power putton have no effect Computer does not appear on the network No BSOD, no memory dump Event logs have no errors or indications of problems near the time of crash. Only messages after reboot indicating that there was a reboot without a clean shutdown. Windows is set to never put the computer to sleep (just the display) Here are the vital stats of the build: OS Windows 8 Pro 64-bit CPU Intel i5-2400 Mobo Intel BOXDP67DE Micro ATX GPU MSI N460GTX Cyclone768D5/OC RAM CORSAIR XMS3 8GB (2 x 4GB) CMX8GX3M2A1333C9 PSU SeaSonic X Series X650 Gold System Drive Samsung 840 Pro 256 GB SSD Data Drive 2 x Western Digital WD20EARS 2TB in hardware RAID 1 Optical Lite-On DVD burner IHAS424-98 And here is the story of how the problem developed and what I've done to diagnose: January 2011, system built with Windows 7 64-bit, runs great. March 2011, Intel replaced the mobo because of the bad sata controllers. October 2012, upgrade to Windows 8 (problems start shortly after). January 2013, system freezes and causes network to fail for the whole house. Unplug the network cable and other devices and PCs can use the internet. Plug it back in, internet goes away for everyone. Reboot and everything is fine. March 2013, install Intel Gigabit CT PCI-E NIC, disable mobo nic in bios. Network strangeness goes away. Freezes are less frequent. Memtest shows no problems (20 passes). Early June 2013, replace Antec PSU with SeaSonic PSU. Mid June 2013, replace OCZ Vertex 2 SSD with Samsung SSD. Late June 2013, get frustrated and hope the community has some good ideas (I'm running out of budget to replace parts). My next plan of attack is setting "Turn off display" to Never and using a screen saver to see how that reacts on the next freeze. It makes me sad to waste power for up to 15 days though. Has anyone out there seen a problem like this? Any ideas on what kind of malfunction would act this way? Ideas of other diagnostic steps to take?

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  • Multiset container appears to stop sorting

    - by Sarah
    I would appreciate help debugging some strange behavior by a multiset container. Occasionally, the container appears to stop sorting. This is an infrequent error, apparent in only some simulations after a long time, and I'm short on ideas. (I'm an amateur programmer--suggestions of all kinds are welcome.) My container is a std::multiset that holds Event structs: typedef std::multiset< Event, std::less< Event > > EventPQ; with the Event structs sorted by their double time members: struct Event { public: explicit Event(double t) : time(t), eventID(), hostID(), s() {} Event(double t, int eid, int hid, int stype) : time(t), eventID( eid ), hostID( hid ), s(stype) {} bool operator < ( const Event & rhs ) const { return ( time < rhs.time ); } double time; ... }; The program iterates through periods of adding events with unordered times to EventPQ currentEvents and then pulling off events in order. Rarely, after some events have been added (with perfectly 'legal' times), events start getting executed out of order. What could make the events ever not get ordered properly? (Or what could mess up the iterator?) I have checked that all the added event times are legitimate (i.e., all exceed the current simulation time), and I have also confirmed that the error does not occur because two events happen to get scheduled for the same time. I'd love suggestions on how to work through this. The code for executing and adding events is below for the curious: double t = 0.0; double nextTimeStep = t + EPID_DELTA_T; EventPQ::iterator eventIter = currentEvents.begin(); while ( t < EPID_SIM_LENGTH ) { // Add some events to currentEvents while ( ( *eventIter ).time < nextTimeStep ) { Event thisEvent = *eventIter; t = thisEvent.time; executeEvent( thisEvent ); eventCtr++; currentEvents.erase( eventIter ); eventIter = currentEvents.begin(); } t = nextTimeStep; nextTimeStep += EPID_DELTA_T; } void Simulation::addEvent( double et, int eid, int hid, int s ) { assert( currentEvents.find( Event(et) ) == currentEvents.end() ); Event thisEvent( et, eid, hid, s ); currentEvents.insert( thisEvent ); }

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  • Visual Studio 2010 and Test Driven Development

    - by devoured elysium
    I'm making my first steps in Test Driven Development with Visual Studio. I have some questions regarding how to implement generic classes with VS 2010. First, let's say I want to implement my own version of an ArrayList. I start by creating the following test (I'm using in this case MSTest): [TestMethod] public void Add_10_Items_Remove_10_Items_Check_Size_Is_Zero() { var myArrayList = new MyArrayList<int>(); for (int i = 0; i < 10; ++i) { myArrayList.Add(i); } for (int i = 0; i < 10; ++i) { myArrayList.RemoveAt(0); } int expected = 0; int actual = myArrayList.Size; Assert.AreEqual(expected, actual); } I'm using VS 2010 ability to hit ctrl + . and have it implement classes/methods on the go. I have been getting some trouble when implementing generic classes. For example, when I define an .Add(10) method, VS doesn't know if I intend a generic method(as the class is generic) or an Add(int number) method. Is there any way to differentiate this? The same can happen with return types. Let's assume I'm implementing a MyStack stack and I want to test if after I push and element and pop it, the stack is still empty. We all know pop should return something, but usually, the code of this test shouldn't care for it. Visual Studio would then think that pop is a void method, which in fact is not what one would want. How to deal with this? For each method, should I start by making tests that are "very specific" such as is obvious the method should return something so I don't get this kind of ambiguity? Even if not using the result, should I have something like int popValue = myStack.Pop() ? How should I do tests to generic classes? Only test with one generic kind of type? I have been using ints, as they are easy to use, but should I also test with different kinds of objects? How do you usually approach this? I see there is a popular tool called TestDriven for .NET. With VS 2010 release, is it still useful, or a lot of its features are now part of VS 2010, rendering it kinda useless? Thanks

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  • Conceptual inheritance implementation

    - by TheSENDER
    Hi there, I'm writing a spatial data structure and I have a doubt about what's the best NODE implementation. According to my design I have an abstract node entity and three classes which inherit from it: EMPTYNODE, FULLNODE, INTERNALNODE. The first one has no particular data. The second one has 1 reference to a generic element. The third one has 2 references to other nodes. I have found several ways to implement this situation (that I have already coded) but I can't decide what's the best. The first solution that I have found is to use a single class Node that potentially performs all the operation in this way: private static class Node { private Elem elem = null; private Node left = null, right = null; public Elem getElem() { assert isFull(); return elem; } public boolean isEmpty() { return elem == null && left == null; } public boolean isFull() { return elem != null; } public boolean isInternal() { return elem == null && left != null; } } The second solution is to write an explicit division by classes where every class offers only its methods. Obviously in this way we are obliged to perform several casts to the node objects. private static abstract class Node { public abstract boolean isEmpty(); public abstract boolean isFull(); public abstract boolean isInternal(); } private static class FullNode extends Node{ private ITriangle elem; @Override public boolean isEmpty() { return false; } @Override public final boolean isFull() { return true; } @Override public final boolean isInternal() { return false; } public Elem getElem() { return elem; } } The third one solution is to use the inheritance allowing every classes to offer all the methods, but the object type should by check by "isEmpty()" and similar methods. In case of wrong call we'll throw an exception. private static abstract class Node { public abstract boolean isEmpty(); public abstract boolean isFull(); public abstract boolean isInternal(); public abstract Elem getElem(); } private static class Empty extends Node{ @Override public boolean isEmpty() { return true; } @Override public final boolean isFull() { return false; } @Override public final boolean isInternal() { return false; } @Override public Elem getElem() { throw new AssertionError(); } } What do you think about these three solutions? Which one would you use? Any other ideas? Thanks for your help. Every idea will be appreciated.

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  • C++ constructor problem, values not being set

    - by 2Real
    Hi, I'm new to C++ and I'm trying to figure out this problem I'm having with my constructor for one of my classes. What happens is... all my variables are initialized properly except two (health and type). #pragma once #include <irrlicht.h> #include <vector> #include <cassert> using namespace irr; using namespace core; using namespace scene; enum { PLAYER = 0, NPC = 1, SOLDIER = 2, CHAINGUNNER = 3 }; class Model { public: Model(void); Model(int id, std::vector<ISceneNode*> modelVec, int modType); ~Model(void); std::vector<int> path; std::vector<ISceneNode*> model; int endNode; int type; int animate; int health; u32 lastAnimation; private: int mId; }; #include "Model.h" Model::Model(void) { //assert(false); } Model::Model(int id, std::vector<ISceneNode*> modelVec, int modType) { path = std::vector<int>(); model = modelVec; endNode = 0; type = modType; animate = 0; health = 100; lastAnimation = 0; mId = id; } Model::~Model(void) {} I create a model with Model soldier(id, model, SOLDIER) Everything is set properly except type and health. I've tried many different things, but I cannot figure out my problem. I'm not sure but the default constructor is being called. It doesn't make sense because I make no called to that constructor. Thanks,

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  • What "Drained" mean in this llstatus result?

    - by xslittlegrass
    I'm trying to run jobs on the cluster of our university, and I come across this result when I trying to see the status of the cluster: llstatus Name Schedd InQ Act Startd Run LdAvg Idle Arch OpSys pandora001 Down 0 0 Run 29 41.04 9999 POWER7 AIX61 pandora002 Down 0 0 Busy 32 32.06 9999 POWER7 AIX61 pandora003 Down 0 0 Drned 0 0.03 9999 POWER7 AIX61 pandora004 Down 0 0 Busy 32 32.07 9999 POWER7 AIX61 pandora005 Down 0 0 Busy 32 32.02 9999 POWER7 AIX61 pandora006 Down 0 0 Busy 32 34.01 9999 POWER7 AIX61 pandora007 Down 0 0 Busy 32 32.02 9999 POWER7 AIX61 pandora008 Down 0 0 Drned 0 0.00 9999 POWER7 AIX61 pandora1 Avail 15 5 Idle 0 0.00 86 POWER7 AIX61 llstatus -R Machine Consumable Resource(Available, Total) ------------------------------ ------------------------------------------------- pandora001 ConsumableCpus< 28-31 >< 0-31 > ConsumableMemory(28.297 gb,124.000 gb)+ pandora002 ConsumableCpus< >< 0-31 > ConsumableMemory(14.625 gb,124.000 gb)+ pandora003 ConsumableCpus< 0-31 >< 0-31 > ConsumableMemory(124.000 gb,124.000 gb)+ pandora004 ConsumableCpus< >< 0-31 > ConsumableMemory(28.000 gb,124.000 gb)+ pandora005 ConsumableCpus< >< 0-31 > ConsumableMemory(28.000 gb,124.000 gb)+ pandora006 ConsumableCpus< >< 0-31 > ConsumableMemory(14.625 gb,124.000 gb)+ pandora007 ConsumableCpus< >< 0-31 > ConsumableMemory(5.250 gb,124.000 gb)+ pandora008 ConsumableCpus< 0-31 >< 0-31 > ConsumableMemory(124.000 gb,124.000 gb)+ pandora1 ConsumableCpus< 0-7 >< 0-7 > ConsumableMemory(32.000 gb,32.000 gb) It seems that the pandora003 and pandora008 are in the status of "Drned". What does that mean? Why I can't use the resources of at thoes nodes? Thanks.

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  • Followup: Python 2.6, 3 abstract base class misunderstanding

    - by Aaron
    I asked a question at Python 2.6, 3 abstract base class misunderstanding. My problem was that python abstract base classes didn't work quite the way I expected them to. There was some discussion in the comments about why I would want to use ABCs at all, and Alex Martelli provided an excellent answer on why my use didn't work and how to accomplish what I wanted. Here I'd like to address why one might want to use ABCs, and show my test code implementation based on Alex's answer. tl;dr: Code after the 16th paragraph. In the discussion on the original post, statements were made along the lines that you don't need ABCs in Python, and that ABCs don't do anything and are therefore not real classes; they're merely interface definitions. An abstract base class is just a tool in your tool box. It's a design tool that's been around for many years, and a programming tool that is explicitly available in many programming languages. It can be implemented manually in languages that don't provide it. An ABC is always a real class, even when it doesn't do anything but define an interface, because specifying the interface is what an ABC does. If that was all an ABC could do, that would be enough reason to have it in your toolbox, but in Python and some other languages they can do more. The basic reason to use an ABC is when you have a number of classes that all do the same thing (have the same interface) but do it differently, and you want to guarantee that that complete interface is implemented in all objects. A user of your classes can rely on the interface being completely implemented in all classes. You can maintain this guarantee manually. Over time you may succeed. Or you might forget something. Before Python had ABCs you could guarantee it semi-manually, by throwing NotImplementedError in all the base class's interface methods; you must implement these methods in derived classes. This is only a partial solution, because you can still instantiate such a base class. A more complete solution is to use ABCs as provided in Python 2.6 and above. Template methods and other wrinkles and patterns are ideas whose implementation can be made easier with full-citizen ABCs. Another idea in the comments was that Python doesn't need ABCs (understood as a class that only defines an interface) because it has multiple inheritance. The implied reference there seems to be Java and its single inheritance. In Java you "get around" single inheritance by inheriting from one or more interfaces. Java uses the word "interface" in two ways. A "Java interface" is a class with method signatures but no implementations. The methods are the interface's "interface" in the more general, non-Java sense of the word. Yes, Python has multiple inheritance, so you don't need Java-like "interfaces" (ABCs) merely to provide sets of interface methods to a class. But that's not the only reason in software development to use ABCs. Most generally, you use an ABC to specify an interface (set of methods) that will likely be implemented differently in different derived classes, yet that all derived classes must have. Additionally, there may be no sensible default implementation for the base class to provide. Finally, even an ABC with almost no interface is still useful. We use something like it when we have multiple except clauses for a try. Many exceptions have exactly the same interface, with only two differences: the exception's string value, and the actual class of the exception. In many exception clauses we use nothing about the exception except its class to decide what to do; catching one type of exception we do one thing, and another except clause catching a different exception does another thing. According to the exception module's doc page, BaseException is not intended to be derived by any user defined exceptions. If ABCs had been a first class Python concept from the beginning, it's easy to imagine BaseException being specified as an ABC. But enough of that. Here's some 2.6 code that demonstrates how to use ABCs, and how to specify a list-like ABC. Examples are run in ipython, which I like much better than the python shell for day to day work; I only wish it was available for python3. Your basic 2.6 ABC: from abc import ABCMeta, abstractmethod class Super(): __metaclass__ = ABCMeta @abstractmethod def method1(self): pass Test it (in ipython, python shell would be similar): In [2]: a = Super() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Super with abstract methods method1 Notice the end of the last line, where the TypeError exception tells us that method1 has not been implemented ("abstract methods method1"). That was the method designated as @abstractmethod in the preceding code. Create a subclass that inherits Super, implement method1 in the subclass and you're done. My problem, which caused me to ask the original question, was how to specify an ABC that itself defines a list interface. My naive solution was to make an ABC as above, and in the inheritance parentheses say (list). My assumption was that the class would still be abstract (can't instantiate it), and would be a list. That was wrong; inheriting from list made the class concrete, despite the abstract bits in the class definition. Alex suggested inheriting from collections.MutableSequence, which is abstract (and so doesn't make the class concrete) and list-like. I used collections.Sequence, which is also abstract but has a shorter interface and so was quicker to implement. First, Super derived from Sequence, with nothing extra: from abc import abstractmethod from collections import Sequence class Super(Sequence): pass Test it: In [6]: a = Super() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Super with abstract methods __getitem__, __len__ We can't instantiate it. A list-like full-citizen ABC; yea! Again, notice in the last line that TypeError tells us why we can't instantiate it: __getitem__ and __len__ are abstract methods. They come from collections.Sequence. But, I want a bunch of subclasses that all act like immutable lists (which collections.Sequence essentially is), and that have their own implementations of my added interface methods. In particular, I don't want to implement my own list code, Python already did that for me. So first, let's implement the missing Sequence methods, in terms of Python's list type, so that all subclasses act as lists (Sequences). First let's see the signatures of the missing abstract methods: In [12]: help(Sequence.__getitem__) Help on method __getitem__ in module _abcoll: __getitem__(self, index) unbound _abcoll.Sequence method (END) In [14]: help(Sequence.__len__) Help on method __len__ in module _abcoll: __len__(self) unbound _abcoll.Sequence method (END) __getitem__ takes an index, and __len__ takes nothing. And the implementation (so far) is: from abc import abstractmethod from collections import Sequence class Super(Sequence): # Gives us a list member for ABC methods to use. def __init__(self): self._list = [] # Abstract method in Sequence, implemented in terms of list. def __getitem__(self, index): return self._list.__getitem__(index) # Abstract method in Sequence, implemented in terms of list. def __len__(self): return self._list.__len__() # Not required. Makes printing behave like a list. def __repr__(self): return self._list.__repr__() Test it: In [34]: a = Super() In [35]: a Out[35]: [] In [36]: print a [] In [37]: len(a) Out[37]: 0 In [38]: a[0] --------------------------------------------------------------------------- IndexError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() /home/aaron/projects/test/test.py in __getitem__(self, index) 10 # Abstract method in Sequence, implemented in terms of list. 11 def __getitem__(self, index): ---> 12 return self._list.__getitem__(index) 13 14 # Abstract method in Sequence, implemented in terms of list. IndexError: list index out of range Just like a list. It's not abstract (for the moment) because we implemented both of Sequence's abstract methods. Now I want to add my bit of interface, which will be abstract in Super and therefore required to implement in any subclasses. And we'll cut to the chase and add subclasses that inherit from our ABC Super. from abc import abstractmethod from collections import Sequence class Super(Sequence): # Gives us a list member for ABC methods to use. def __init__(self): self._list = [] # Abstract method in Sequence, implemented in terms of list. def __getitem__(self, index): return self._list.__getitem__(index) # Abstract method in Sequence, implemented in terms of list. def __len__(self): return self._list.__len__() # Not required. Makes printing behave like a list. def __repr__(self): return self._list.__repr__() @abstractmethod def method1(): pass class Sub0(Super): pass class Sub1(Super): def __init__(self): self._list = [1, 2, 3] def method1(self): return [x**2 for x in self._list] def method2(self): return [x/2.0 for x in self._list] class Sub2(Super): def __init__(self): self._list = [10, 20, 30, 40] def method1(self): return [x+2 for x in self._list] We've added a new abstract method to Super, method1. This makes Super abstract again. A new class Sub0 which inherits from Super but does not implement method1, so it's also an ABC. Two new classes Sub1 and Sub2, which both inherit from Super. They both implement method1 from Super, so they're not abstract. Both implementations of method1 are different. Sub1 and Sub2 also both initialize themselves differently; in real life they might initialize themselves wildly differently. So you have two subclasses which both "is a" Super (they both implement Super's required interface) although their implementations are different. Also remember that Super, although an ABC, provides four non-abstract methods. So Super provides two things to subclasses: an implementation of collections.Sequence, and an additional abstract interface (the one abstract method) that subclasses must implement. Also, class Sub1 implements an additional method, method2, which is not part of Super's interface. Sub1 "is a" Super, but it also has additional capabilities. Test it: In [52]: a = Super() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Super with abstract methods method1 In [53]: a = Sub0() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Sub0 with abstract methods method1 In [54]: a = Sub1() In [55]: a Out[55]: [1, 2, 3] In [56]: b = Sub2() In [57]: b Out[57]: [10, 20, 30, 40] In [58]: print a, b [1, 2, 3] [10, 20, 30, 40] In [59]: a, b Out[59]: ([1, 2, 3], [10, 20, 30, 40]) In [60]: a.method1() Out[60]: [1, 4, 9] In [61]: b.method1() Out[61]: [12, 22, 32, 42] In [62]: a.method2() Out[62]: [0.5, 1.0, 1.5] [63]: a[:2] Out[63]: [1, 2] In [64]: a[0] = 5 --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: 'Sub1' object does not support item assignment Super and Sub0 are abstract and can't be instantiated (lines 52 and 53). Sub1 and Sub2 are concrete and have an immutable Sequence interface (54 through 59). Sub1 and Sub2 are instantiated differently, and their method1 implementations are different (60, 61). Sub1 includes an additional method2, beyond what's required by Super (62). Any concrete Super acts like a list/Sequence (63). A collections.Sequence is immutable (64). Finally, a wart: In [65]: a._list Out[65]: [1, 2, 3] In [66]: a._list = [] In [67]: a Out[67]: [] Super._list is spelled with a single underscore. Double underscore would have protected it from this last bit, but would have broken the implementation of methods in subclasses. Not sure why; I think because double underscore is private, and private means private. So ultimately this whole scheme relies on a gentleman's agreement not to reach in and muck with Super._list directly, as in line 65 above. Would love to know if there's a safer way to do that.

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  • Our Look at the Internet Explorer 9 Platform Preview

    - by Asian Angel
    Have you been hearing all about Microsoft’s work on Internet Explorer 9 and are curious about it? If you are wanting a taste of the upcoming release then join us as we take a look at the Internet Explorer 9 Platform Preview. Note: Windows Vista and Server 2008 users may need to install a Platform Update (see link at bottom for more information). Getting Started If you are curious about the systems that the platform preview will operate on here is an excerpt from the FAQ page (link provided below). There are two important points of interest here: The platform preview does not replace your regular Internet Explorer installation The platform preview (and the final version of Internet Explorer 9) will not work on Windows XP There really is not a lot to the install process…basically all that you will have to deal with is the “EULA Window” and the “Install Finished Window”. Note: The platform preview will install to a “Program Files Folder” named “Internet Explorer Platform Preview”. Internet Explorer 9 Platform Preview in Action When you start the platform preview up for the first time you will be presented with the Internet Explorer 9 Test Drive homepage. Do not be surprised that there is not a lot to the UI at this time…but you can get a good idea of how Internet Explorer will act. Note: You will not be able to alter the “Homepage” for the platform preview. Of the four menus available there are two that will be of interest to most people…the “Page & Debug Menus”. If you go to navigate to a new webpage you will need to go through the “Page Menu” unless you have installed the Address Bar Mini-Tool (shown below). Want to see what a webpage will look like in an older version of Internet Explorer? Then choose your version in the “Debug Menu”. We did find it humorous that IE6 was excluded from the choices offered. Here is what the URL entry window looks like if you are using the “Page Menu” to navigate between websites. Here is the main page of the site here displayed in “IE9 Mode”…looking good. Here is the main page viewed in “Forced IE5 Document Mode”. There were some minor differences (colors, sidebar, etc.) in how the main page displayed in comparison to “IE9 Mode”. Being able to switch between modes makes for an interesting experience… As you can see there is not much to the “Context Menu” at the moment. Notice the slightly altered icon for the platform preview… “Add” an Address Bar of Sorts If you would like to use a “make-shift” Address Bar with the platform preview you can set up the portable file (IE9browser.exe) for the Internet Explorer 9 Test Platform Addressbar Mini-Tool. Just place it in an appropriate folder, create a shortcut for it, and it will be ready to go. Here is a close look at the left side of the Address Bar Mini-Tool. You can try to access “IE Favorites” but may have sporadic results like those we experienced during our tests. Note: The Address Bar Mini-Tool will not line up perfectly with the platform preview but still makes a nice addition. And a close look at the right side of the Address Bar Mini-Tool. In order to completely shut down the Address Bar Mini-Tool you will need to click on “Close”. Each time that you enter an address into the Address Bar Mini-Tool it will open a new window/instance of the platform preview. Note: During our tests we noticed that clicking on “Home” in the “Page Menu” opened the previously viewed website but once we closed and restarted the platform preview the test drive website was the starting/home page again. Even if the platform preview is not running the Address Bar Mini-Tool can still run as shown here. Note: You will not be able to move the Address Bar Mini-Tool from its’ locked-in position at the top of the screen. Now for some fun. With just the Address Bar Mini-Tool open you can enter an address and cause the platform preview to open. Here is our example from above now open in the platform preview…good to go. Conclusion During our tests we did experience the occasional crash but overall we were pleased with the platform preview’s performance. The platform preview handled rather well and definitely seemed much quicker than Internet Explorer 8 on our test system (a definite bonus!). If you are an early adopter then this could certainly get you in the mood for the upcoming beta releases! Links Download the Internet Explorer 9 Preview Platform Download the Internet Explorer 9 Test Platform Addressbar Mini-Tool Information about Platform Update for Windows Vista & Server 2008 View the Internet Explorer 9 Platform Preview FAQ Similar Articles Productive Geek Tips Mysticgeek Blog: A Look at Internet Explorer 8 Beta 1 on Windows XPMake Ctrl+Tab in Internet Explorer 7 Use Most Recent OrderRemove ISP Text or Corporate Branding from Internet Explorer Title BarWhy Can’t I Turn the Details/Preview Panes On or Off in Windows Vista Explorer?Prevent Firefox or Internet Explorer from Printing the URL on Every Page 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 DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Awesome Lyrics Finder for Winamp & Windows Media Player Download Videos from Hulu Pixels invade Manhattan Convert PDF files to ePub to read on your iPad Hide Your Confidential Files Inside Images Get Wildlife Photography Tips at BBC’s PhotoMasterClasses

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  • Non-Dom Element Event Binding with jQuery

    - by Rick Strahl
    Yesterday I had a short discussion with Dave Reed on Twitter regarding setting up fake ‘events’ on objects that are hookable. jQuery makes it real easy to bind events on DOM elements and with a little bit of extra work (that I didn’t know about) you can also set up binding to non-DOM element ‘event’ bindings. Assume for a second that you have a simple JavaScript object like this: var item = { sku: "wwhelp" , foo: function() { alert('orginal foo function'); } }; and you want to be notified when the foo function is called. You can use jQuery to bind the handler like this: $(item).bind("foo", function () { alert('foo Hook called'); } ); Binding alone won’t actually cause the handler to be triggered so when you call: item.foo(); you only get the ‘original’ message. In order to fire both the original handler and the bound event hook you have to use the .trigger() function: $(item).trigger("foo"); Now if you do the following complete sequence: var item = { sku: "wwhelp" , foo: function() { alert('orginal foo function'); } }; $(item).bind("foo", function () { alert('foo hook called'); } ); $(item).trigger("foo"); You’ll see the ‘hook’ message first followed by the ‘original’ message fired in succession. In other words, using this mechanism you can hook standard object functions and chain events to them in a way similar to the way you can do with DOM elements. The main difference is that the ‘event’ has to be explicitly triggered in order for this to happen rather than just calling the method directly. .trigger() relies on some internal logic that checks for event bindings on the object (attached via an expando property) which .trigger() searches for in its bound event list. Once the ‘event’ is found it’s called prior to execution of the original function. This is pretty useful as it allows you to create standard JavaScript objects that can act as event handlers and are effectively hookable without having to explicitly override event definitions with JavaScript function handlers. You get all the benefits of jQuery’s event methods including the ability to hook up multiple events to the same handler function and the ability to uniquely identify each specific event instance with post fix string names (ie. .bind("MyEvent.MyName") and .unbind("MyEvent.MyName") to bind MyEvent). Watch out for an .unbind() Bug Note that there appears to be a bug with .unbind() in jQuery that doesn’t reliably unbind an event and results in a elem.removeEventListener is not a function error. The following code demonstrates: var item = { sku: "wwhelp", foo: function () { alert('orginal foo function'); } }; $(item).bind("foo.first", function () { alert('foo hook called'); }); $(item).bind("foo.second", function () { alert('foo hook2 called'); }); $(item).trigger("foo"); setTimeout(function () { $(item).unbind("foo"); // $(item).unbind("foo.first"); // $(item).unbind("foo.second"); $(item).trigger("foo"); }, 3000); The setTimeout call delays the unbinding and is supposed to remove the event binding on the foo function. It fails both with the foo only value (both if assigned only as “foo” or “foo.first/second” as well as when removing both of the postfixed event handlers explicitly. Oddly the following that removes only one of the two handlers works: setTimeout(function () { //$(item).unbind("foo"); $(item).unbind("foo.first"); // $(item).unbind("foo.second"); $(item).trigger("foo"); }, 3000); this actually works which is weird as the code in unbind tries to unbind using a DOM method that doesn’t exist. <shrug> A partial workaround for unbinding all ‘foo’ events is the following: setTimeout(function () { $.event.special.foo = { teardown: function () { alert('teardown'); return true; } }; $(item).unbind("foo"); $(item).trigger("foo"); }, 3000); which is a bit cryptic to say the least but it seems to work more reliably. I can’t take credit for any of this – thanks to Dave Reed and Damien Edwards who pointed out some of these behaviors. I didn’t find any good descriptions of the process so thought it’d be good to write it down here. Hope some of you find this helpful.© Rick Strahl, West Wind Technologies, 2005-2010Posted in jQuery  

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  • Last week I was presented with a Microsoft MVP award in Virtual Machines – time to thank all who hel

    - by Liam Westley
    MVP in Virtual Machines Last week, on 1st April, I received an e-mail from Microsoft letting me know that I had been presented with a 2010 Microsoft® MVP Award for outstanding contributions in Virtual Machine technical communities during the past year.   It was an honour to be nominated, and is a great reflection on the vibrancy of the UK user group community which made this possible. Virtualisation for developers, not just IT Pros I consider it a special honour as my expertise in virtualisation is as a software developer utilising virtual machines to aid my software development, rather than an IT Pro who manages data centre and network infrastructure.  I’ve been on a minor mission over the past few years to enthuse developers in a topic usually seen as only for network admins, but which can make their life a whole lot easier once understood properly. Continuous learning is fun In 1676, the scientist Isaac Newton, in a letter to Robert Hooke used the phrase (http://www.phrases.org.uk/meanings/268025.html) ‘If I have seen a little further it is by standing on the shoulders of Giants’ I’m a nuclear physicist by education, so I am more than comfortable that any knowledge I have is based on the work of others.  Although far from a science, software development and IT is equally built upon the work of others. It’s one of the reasons I despise software patents. So in that sense this MVP award is a result of all the great minds that have provided virtualisation solutions for me to talk about.  I hope that I have always acknowledged those whose work I have used when blogging or giving presentations, and that I have executed my responsibility to share any knowledge gained as widely as possible. Thanks to all those who helped – a big thanks to the UK user group community I reckon this journey started in 2003 when I started attending a user group called the London .Net Users Group (http://www.dnug.org.uk) started by a nice chap called Ian Cooper. The great thing about Ian was that he always encouraged non professional speakers to take the stage at the user group, and my first ever presentation was on 30th September 2003; SQL Server CE 2.0 and the.NET Compact Framework. In 2005 Ian Cooper was on the committee for the first DeveloperDeveloperDeveloper! day, the free community conference held at Microsoft’s UK HQ in Thames Valley park in Reading.  He encouraged me to take part and so on 14th May 2005 I presented a talk previously given to the London .Net User Group on Simplifying access to multiple DB providers in .NET.  From that point on I definitely had the bug; presenting at DDD2, DDD3, groking at DDD4 and SQLBits I and after a break, DDD7, DDD Scotland and DDD8.  What definitely made me keen was the encouragement and infectious enthusiasm of some of the other DDD organisers; Craig Murphy, Barry Dorrans, Phil Winstanley and Colin Mackay. During the first few DDD events I met the Dave McMahon and Richard Costall from NxtGenUG who made it easy to start presenting at their user groups.  Along the way I’ve met a load of great user group organisers; Guy Smith-Ferrier of the .Net Developer Network, Jimmy Skowronski of GL.Net and the double act of Ray Booysen and Gavin Osborn behind what was Vista Squad and is now Edge UG. Final thanks to those who suggested virtualisation as a topic ... Final thanks have to go the people who inspired me to create my Virtualisation for Developers talk.  Toby Henderson (@holytshirt) ensured I took notice of Sun’s VirtualBox, Peter Ibbotson for being a fine sounding board at the Kew Railway over quite a few Adnam’s Broadside and to Guy Smith-Ferrier for allowing his user group to be the guinea pigs for the talk before it was seen at DDD7.  Thanks to all of you I now know much more about virtualisation than I would have thought possible and it continues to be great fun. Conclusion If this was an academy award acceptance speech I would have been cut off after the first few paragraphs, so well done if you made it this far.  I’ll be doing my best to do justice to the MVP award and the UK community.  I’m fortunate in having a new employer who considers presenting at user groups as a good thing, so don’t expect me to stop any time soon. If you’ve never seen me in action, then you can view the original DDD7 Virtualisation for Developers presentation (filmed by the Microsoft Channel 9 team) as part of the full DDD7 video list here, http://www.craigmurphy.com/blog/?p=1591.  Also thanks to Craig Murphy’s fine video work you can also view my latest DDD8 presentation on Commercial Software Development, here, http://vimeo.com/9216563 P.S. If I’ve missed anyone out, do feel free to lambast me in comments, it’s your duty.

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  • Social Network Updates: While You Were Busy Marketing 2

    - by Mike Stiles
    Since social moves at the speed of data, it’s already time for another update, as we did back in April, on the changes the various social networks have made or gone through while you were busy marketing. Facebook There’s a lot of talk Facebook’s developing a mobile product to act like Flipboard and surface news, from both users and media outlets. The biggest news was Facebook/Instagram’s introduction of 15-second videos, enhanced with with filters, to take some of Vine’s candy. You can also delete parts of videos and rerecord them, and there’s image stabilization. Facebook’s ad revenue is coming along just fine, thank you very much. 35% quarter-to-quarter growth in Q2. And it looks like new formats like Mobile App Install Ads and Unpublished Page Posts are adding to the mix. If you don’t already, you’ll soon see a little camera in comment boxes letting you insert photos right into the comments you make. The drive toward “more visual” continues. The other big news is Facebook’s adoption of our Twitter friend, the hashtag. Adding # sets apart the post topic so it can be easily found or discovered. It’s also being added to Google Plus, Tumblr, and Pinterest. Twitter Want to send someone a promoted tweet when they’re in range of your store? That could be happening by the end of this year. Some users have been seeing automatic in-stream previews of images on Twitter.com. Right now it’s images in your own tweets, but we can assume all tweets are next. Get your followers organized! Twitter raised the limit on the number of lists you can create from 20 to 1,000. They also raised the number of accounts you can have in a list from 500 to 5,000. Twitter started notifying you when someone favorites a tweet you’re mentioned in or re-tweets a tweet you re-tweeted. Anyway, it’s the first time Twitter’s notified you about indirect interactions like that. Who’s afraid of Instagram? A study shows 6-second Vine videos are being posted to Twitter at the rate of 9/second, up from 5/second 2 months ago. Vine has over 13 million users and branded Vines are 4x more likely to be shared than video ads. Google Plus Now featuring a 3-column redesigned stream, and images that take up a whole column. And photo filters Auto Highlight and Auto Awesome work to turn your photos into a real show. Google Hangouts is the workhorse for all Google messaging now, it’s not just an online chat with 9 people anymore. Google Plus Dashboard improves the connection between your company’s Google Plus business page and your Google Plus Local. Updates go out across all Google properties and you can do your managing from the dashboard. With Google Plus’ authorship system, you can build “Author Rank” based on what you write and put on the web. If your stuff is +1’ed and shared a lot, you’re the real deal and there are search result benefits. LinkedIn "Who's Viewed Your Updates" shows you what you’ve shared recently, who saw it and what they did about it in real-time. “Influencers” is, well, influential. Traffic to all LI news products has gone up 8x since it was introduced. LinkedIn is quickly figuring out how to get users to stick around awhile. You and your brand can post images and documents in status updates now. In fact, that whole “document posting” thing is making some analysts wonder if LinkedIn will drift on over to the Dropboxes and YouSendIts of the world. C’mon, admit it. Your favorite part of LinkedIn is being able to see who’s viewed your profile. Now you’ve got even more info and can see what/who you have in common. Premium users get even deeper insights about how people are finding them. If you’re a big fan of security, you’ll love that LinkedIn started offering two-factor authentication (2FA). It’s optional, but step 2 is a one-time code texted to your registered mobile. Pinterest A study showed pins have a looong shelf life compared to other social net posts. “Clicks kept coming for 30 days and beyond.” Most pins are timeless, and the infinite scroll causes people to see older pins. Is it a keeper? Pinterest jumped 82% to 54 million users in the past year. It’s valued at $2.5 billion and is one of the biggest sources of referral traffic there is. That said, CEO Ben Silbermann adds, "Right now, we don't make money." A new search feature stops you from having to endlessly scroll through your own pins looking for that waterfall picture you posted. Simply select “just my pins” in the search bar. New "Rich Pins" lets brands add info like price and availability to pins that can be updated daily via a data feed from your merchant site. Not so fast, you have to apply to Pinterest for it first. Like other social nets, Pinterest does not allow sexual content, nudity, or even partial nudity. However…some art contains nudity, and Pinterest wants to allow art. What constitutes “art” will be judged by…what we have to assume are Pinterest employees who love their job. @mikestilesPhoto: stock.xchng, Tim Marmon

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  • Code Contracts: Hiding ContractException

    - by DigiMortal
    It’s time to move on and improve my randomizer I wrote for an example of static checking of code contracts. In this posting I will modify contracts and give some explanations about pre-conditions and post-conditions. Also I will show you how to avoid ContractExceptions and how to replace them with your own exceptions. As a first thing let’s take a look at my randomizer. public class Randomizer {     public static int GetRandomFromRange(int min, int max)     {         var rnd = new Random();         return rnd.Next(min, max);     }       public static int GetRandomFromRangeContracted(int min, int max)     {         Contract.Requires(min < max, "Min must be less than max");           var rnd = new Random();         return rnd.Next(min, max);     } } We have some problems here. We need contract for method output and we also need some better exception handling mechanism. As ContractException as type is hidden from us we have to switch from ContractException to some other Exception type that we can catch. Adding post-condition Pre-conditions are contracts for method’s input interface. Read it as follows: pre-conditions make sure that all conditions for method’s successful run are met. Post-conditions are contracts for output interface of method. So, post-conditions are for output arguments and return value. My code misses the post-condition that checks return value. Return value in this case must be greater or equal to minimum value and less or equal to maximum value. To make sure that method can run only the correct value I added call to Contract.Ensures() method. public static int GetRandomFromRangeContracted(int min, int max) {     Contract.Requires(min < max, "Min must be less than max");       Contract.Ensures(         Contract.Result<int>() >= min &&         Contract.Result<int>() <= max,         "Return value is out of range"     );       var rnd = new Random();     return rnd.Next(min, max); } I think that the line I added does not need any further comments. Avoiding ContractException for input interface ContractException lives in hidden namespace and we cannot see it at design time. But it is common exception type for all contract exceptions that we do not switch over to some other type. The case of Contract.Requires() method is simple: we can tell it what kind of exception we need if something goes wrong with contract it ensures. public static int GetRandomFromRangeContracted(int min, int max) {     Contract.Requires<ArgumentOutOfRangeException>(         min < max,         "Min must be less than max"     );       Contract.Ensures(         Contract.Result<int>() >= min &&         Contract.Result<int>() <= max,         "Return value is out of range"     );       var rnd = new Random();     return rnd.Next(min, max); } Now, if we violate the input interface contract giving min value that is not less than max value we get ArgumentOutOfRangeException. Avoiding ContractException for output interface Output interface is more complex to control. We cannot give exception type there and hope that this type of exception will be thrown if something goes wrong. Instead we have to use delegate that gathers information about problem and throws the exception we expect to be thrown. From documentation you can find the following example about the delegate I mentioned. Contract.ContractFailed += (sender, e) => {     e.SetHandled();     e.SetUnwind(); // cause code to abort after event     Assert.Fail(e.FailureKind.ToString() + ":" + e.DebugMessage); }; We can use this delegate to throw the Exception. Let’s move the code to separate method too. Here is our method that uses now ContractException hiding. public static int GetRandomFromRangeContracted(int min, int max) {     Contract.Requires(min < max, "Min must be less than max");       Contract.Ensures(         Contract.Result<int>() >= min &&         Contract.Result<int>() <= max,         "Return value is out of range"     );     Contract.ContractFailed += Contract_ContractFailed;       var rnd = new Random();     return rnd.Next(min, max)+1000; } And here is the delegate that creates exception. public static void Contract_ContractFailed(object sender,     ContractFailedEventArgs e) {     e.SetHandled();     e.SetUnwind();       throw new Exception(e.FailureKind.ToString() + ":" + e.Message); } Basically we can do in this delegate whatever we like to do with output interface errors. We can even introduce our own contract exception type. As you can see later then ContractFailed event is very useful at unit testing.

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  • Run Your Tests With Any NUnit Version

    - by Alois Kraus
    I always thought that the NUnit test runners and the test assemblies need to reference the same NUnit.Framework version. I wanted to be able to run my test assemblies with the newest GUI runner (currently 2.5.3). Ok so all I need to do is to reference both NUnit versions the newest one and the official for the current project. There is a nice article form Kent Bogart online how to reference the same assembly multiple times with different versions. The magic works by referencing one NUnit assembly with an alias which does prefix all types inside it. Then I could decorate my tests with the TestFixture and Test attribute from both NUnit versions and everything worked fine except that this was ugly. After playing a little bit around to make it simpler I found that I did not need to reference both NUnit.Framework assemblies. The test runners do not require the TestFixture and Test attribute in their specific version. That is really neat since the test runners are instructed by attributes what to do in a declarative way there is really no need to tie the runners to a specific version. At its core NUnit has this little method hidden to find matching TestFixtures and Tests   public bool CanBuildFrom(Type type) {     if (!(!type.IsAbstract || type.IsSealed))     {         return false;     }     return (((Reflect.HasAttribute(type,           "NUnit.Framework.TestFixtureAttribute", true) ||               Reflect.HasMethodWithAttribute(type, "NUnit.Framework.TestAttribute"       , true)) ||               Reflect.HasMethodWithAttribute(type, "NUnit.Framework.TestCaseAttribute"   , true)) ||               Reflect.HasMethodWithAttribute(type, "NUnit.Framework.TheoryAttribute"     , true)); } That is versioning and backwards compatibility at its best. I tell NUnit what to do by decorating my tests classes with NUnit Attributes and the runner executes my intent without the need to bind me to a specific version. The contract between NUnit versions is actually a bit more complex (think of AssertExceptions) but this is also handled nicely by using not the concrete type but simply to check for the catched exception type by string. What can we learn from this? Versioning can be easy if the contract is small and the users of your library use it in a declarative way (Attributes). Everything beyond it will force you to reference several versions of the same assembly with all its consequences. Type equality is lost between versions so none of your casts will work. That means that you cannot simply use IBigInterface in two versions. You will need a wrapper to call the correct versioned one. To get out of this mess you can use one (and only one) version agnostic driver to encapsulate your business logic from the concrete versions. This is of course more work but as NUnit shows it can be easy. Simplicity is therefore not a nice thing to have but also requirement number one if you intend to make things more complex in version two and want to support any version (older and newer). Any interaction model above easy will not be maintainable. There are different approached to versioning. Below are my own personal observations how versioning works within the  .NET Framwork and NUnit.   Versioning Models 1. Bug Fixing and New Isolated Features When you only need to fix bugs there is no need to break anything. This is especially true when you have a big API surface. Microsoft did this with the .NET Framework 3.0 which did leave the CLR as is but delivered new assemblies for the features WPF, WCF and Windows Workflow Foundations. Their basic model was that the .NET 2.0 assemblies were declared as red assemblies which must not change (well mostly but each change was carefully reviewed to minimize the risk of breaking changes as much as possible) whereas the new green assemblies of .NET 3,3.5 did not have such obligations since they did implement new unrelated features which did not have any impact on the red assemblies. This is versioning strategy aimed at maximum compatibility and the delivery of new unrelated features. If you have a big API surface you should strive hard to do the same or you will break your customers code with every release. 2. New Breaking Features There are times when really new things need to be added to an existing product. The .NET Framework 4.0 did change the CLR in many ways which caused subtle different behavior although the API´s remained largely unchanged. Sometimes it is possible to simply recompile an application to make it work (e.g. changed method signature void Func() –> bool Func()) but behavioral changes need much more thought and cannot be automated. To minimize the impact .NET 2.0,3.0,3.5 applications will not automatically use the .NET 4.0 runtime when installed but they will keep using the “old” one. What is interesting is that a side by side execution model of both CLR versions (2 and 4) within one process is possible. Key to success was total isolation. You will have 2 GCs, 2 JIT compilers, 2 finalizer threads within one process. The two .NET runtimes cannot talk  (except via the usual IPC mechanisms) to each other. Both runtimes share nothing and run independently within the same process. This enables Explorer plugins written for the CLR 2.0 to work even when a CLR 4 plugin is already running inside the Explorer process. The price for isolation is an increased memory footprint because everything is loaded and running two times.   3. New Non Breaking Features It really depends where you break things. NUnit has evolved and many different Assert, Expect… methods have been added. These changes are all localized in the NUnit.Framework assembly which can be easily extended. As long as the test execution contract (TestFixture, Test, AssertException) remains stable it is possible to write test executors which can run tests written for NUnit 10 because the execution contract has not changed. It is possible to write software which executes other components in a version independent way but this is only feasible if the interaction model is relatively simple.   Versioning software is hard and it looks like it will remain hard since you suddenly work in a severely constrained environment when you try to innovate and to keep everything backwards compatible at the same time. These are contradicting goals and do not play well together. The easiest way out of this is to carefully watch what your customers are doing with your software. Minimizing the impact is much easier when you do not need to guess how many people will be broken when this or that is removed.

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  • Psychonauts crashes right after entering load save door

    - by user67974
    Psychonauts crashes right after entering the 'Load Save' door. Here is the terminal output: Shader assembly time: 0.88 seconds Found OpenAL device: 'Simple Directmedia Layer' Found OpenAL device: 'ALSA Software' Found OpenAL device: 'OSS Software' Found OpenAL device: 'PulseAudio Software' Opened OpenAL Device: '(null)' ERROR: CAudioDrv::CAudioDrv->alGenSources reports AL_INVALID_VALUE error. PSYCHONAUTS UNIX FILENAME: corrected 'workresource/sounds/commonfx.isb' to 'WorkResource/Sounds/commonfx.isb' PSYCHONAUTS UNIX FILENAME: corrected 'workresource/sounds/commonvoice.isb' to 'WorkResource/Sounds/commonvoice.isb' PSYCHONAUTS UNIX FILENAME: corrected 'workresource/sounds/commonmusic.isb' to 'WorkResource/Sounds/commonmusic.isb' PSYCHONAUTS UNIX FILENAME: corrected 'workresource/sounds/commonmentalfx.isb' to 'WorkResource/Sounds/commonmentalfx.isb' PSYCHONAUTS UNIX FILENAME: corrected 'workresource/sounds/commonmenfxmem.isb' to 'WorkResource/Sounds/commonmenfxmem.isb' PSYCHONAUTS UNIX FILENAME: corrected 'workresource/sounds/commonfxmem.isb' to 'WorkResource/Sounds/commonfxmem.isb' GameApp::StartUp InitSoundFiles() completed in 0.15 seconds GameApp::StartUp Load some common textures completed in 0.00 seconds WARN: ENGINE: Lua garbage collection starting FreeUnusedBlocksInBuckets released 0 Kb GameApp::StartUp InitEntities() completed in 0.02 seconds PSYCHONAUTS UNIX FILENAME: corrected 'WorkResource/SavedGames/savegameprefs.ini' to 'WorkResource/SAVEDGAMES/savegameprefs.ini' PSYCHONAUTS UNIX FILENAME: corrected 'WorkResource/SavedGames/savegameprefs.ini' to 'WorkResource/SAVEDGAMES/savegameprefs.ini' GameApp::StartUp m_pSaveLoadInterface->Startup() completed in 0.00 seconds GameApp::StartUp m_UserInterface.Setup() completed in 0.00 seconds STUBBED: multisample at EDisplayOptionsWidget (/home/icculus/projects/psychonauts/Source/game/luatest/Game/UIPCDisplayOptions.cpp:97) STUBBED: VK_* at CheckVirtualKey (/home/icculus/projects/psychonauts/Source/CommonLibs/DirectX/SDLInput.cpp:1443) Game: Engine Running hook startup Game: Engine -> SetupGlobalObjects Game: Engine -> SetupLevelMenu Game: Engine -> InitMath GameApp::StartUp InitLua2() completed in 0.00 seconds GameApp::StartUp SetupLevelMenu() completed in 0.00 seconds STUBBED: do we even use this? at InitSocket (/home/icculus/projects/psychonauts/Source/game/luatest/Game/Gameplaylogger.cpp:210) GameApp::StartUp Post-Install total completed in 0.20 seconds Start Up completed in 1.57 seconds UnixMain: StartUp successful.. Working directory: /opt/psychonauts STUBBED: dispatch SDL events at PCMainHandleAnyWindowsMessages (/home/icculus/projects/psychonauts/Source/game/luatest/UnixMain.cpp:56) STUBBED: write me at GetJoystickInput (/home/icculus/projects/psychonauts/Source/CommonLibs/DirectX/SDLInput.cpp:428) STUBBED: write me at GetJoystickActionValue (/home/icculus/projects/psychonauts/Source/CommonLibs/DirectX/SDLInput.cpp:613) PSYCHONAUTS UNIX FILENAME: corrected 'workresource/cutScenes/prerendered/dflogo.bik' to 'WorkResource/cutscenes/prerendered/DFLogo.bik' Prerender subtitle file: workresource\cutScenes\prerendered\dflogo.dfs not found PSYCHONAUTS UNIX FILENAME: corrected 'workresource/cutScenes/prerendered/dflogo.bik' to 'WorkResource/cutscenes/prerendered/DFLogo.bik' STUBBED: fixed function pipeline? at setColorOp (/home/icculus/projects/psychonauts/Source/CommonLibs/DFGraphics/Texture.cpp:2097) STUBBED: fixed function pipeline? at setColorArg1 (/home/icculus/projects/psychonauts/Source/CommonLibs/DFGraphics/Texture.cpp:2106) STUBBED: fixed function pipeline? at setColorArg2 (/home/icculus/projects/psychonauts/Source/CommonLibs/DFGraphics/Texture.cpp:2115) STUBBED: fixed function pipeline? at setAlphaOp (/home/icculus/projects/psychonauts/Source/CommonLibs/DFGraphics/Texture.cpp:2124) STUBBED: fixed function pipeline? at setAlphaArg1 (/home/icculus/projects/psychonauts/Source/CommonLibs/DFGraphics/Texture.cpp:2133) STUBBED: fixed function pipeline? at setAlphaArg2 (/home/icculus/projects/psychonauts/Source/CommonLibs/DFGraphics/Texture.cpp:2142) STUBBED: fixed function pipeline? at setProjected (/home/icculus/projects/psychonauts/Source/CommonLibs/DFGraphics/Texture.cpp:2223) LOC WARN: Could not open Localization file 'Localization/English/_StringTable.lub' STUBBED: memory status at UpdateMemoryTracking (/home/icculus/projects/psychonauts/Source/game/luatest/Game/GameApp.cpp:4884) WARN: Couldn't resize array to 128; out-of-bounds elements are still in use: Vertex Pool, 188 Loading new level 'STMU' STUBBED: Need multithreaded GL at DisplayLoadingScreen (/home/icculus/projects/psychonauts/Source/game/luatest/Game/LoadingScreen.cpp:83) ========================= Memory post unload level ========================= ========================= LOC WARN: Could not open Localization file 'Localization/English/ST_StringTable.lub' DaveD: Info: Texture pack file contains 137 textures Doing a texture readback for locking! Game: Engine Saved[GLOBAL]: InstaHintFord_HostileRecord = [table] Game: Engine Saved[GLOBAL]: InstaHintFord_HostileOrder = [table] WARN: Redundant packfile read: anims\thought_bubble\bubblefirestarting.jan WARN: Redundant packfile read: anims\thought_bubble\bubbleintothemind.jan WARN: Redundant packfile read: anims\thought_bubble\bubbleinvisibility.jan WARN: Redundant packfile read: anims\thought_bubble\bubblepopperfill.jan WARN: Redundant packfile read: anims\thought_bubble\bubbletelekinesis.jan Initializing level script (if there is one) PSYCHONAUTS UNIX FILENAME: corrected 'workresource/sounds/stfx.isb' to 'WorkResource/Sounds/stfx.isb' Game: Engine Reloading goals: Game: Engine Saved[GLOBAL]: NextEncouragement = '/GLZF014TO/ 10' Game: Engine Saved[GLOBAL]: bUsedSalts = 0 Game: Engine Saved[GLOBAL]: bSTEntered = 1 Game: Engine Saved[GLOBAL]: memoriesST = 1 Game: Engine Saved[GLOBAL]: PsiBallColor = 'red' Game: Engine Saved[ST]: lastSubLevel = 'STMU' Game: Engine LOADING LEVEL st.STMU Game: Engine Saved[CA]: CALevelState = 1 Game: Engine Cutscene progression: CS Script moving from state nil to state nil, resultant state nil. Time: 0.124746672809124. * Stack Trace 1: (null) (line -1, file '(none)) () 2: SpawnScript (line -1, file 'C) (global) 3: onBeginLevel (line -1, file '(none)) (field) 4: (null) (line -1, file '(none)) () WARN: Cannot call GetDirectoryListing when running from the DVD Game: Engine Raz spawning at DartStart startpoint VM : LevelScript could not find script 'doorrimlight1' * Stack Trace 1: (null) (line -1, file '(none)) () WARN: (none(-1) SetEntityAlpha LevelScript: NULL script object passed Game: Engine Saved[GLOBAL]: bLoadedFromMainMenu = 1 Game: Engine Saved[GLOBAL]: NextEncouragement = '/GLZF014TO/ 10' Game: Engine Saved[GLOBAL]: NeedRankIncrement = 0 STUBBED: Need multithreaded GL at HideLoadingScreen (/home/icculus/projects/psychonauts/Source/game/luatest/Game/LoadingScreen.cpp:110) WARN: ENGINE: Lua garbage collection starting FreeUnusedBlocksInBuckets released 0 Kb Game: Engine Saved[GLOBAL]: SplineFigmentTVSizex = 4.51434326171875 Game: Engine Saved[GLOBAL]: SplineFigmentTVSizey = 46.38104248046875 Game: Engine Saved[GLOBAL]: SplineFigmentTVSizez = 47.08810424804688 WARN: (none(-1) SetNewAction LevelScript: no string passed ====================== Asset load progression ====================== Initial: 2.518 MB Vertex, 8.688 MB Texture Level : 3.719 MB Vertex, 22.535 MB Texture Scripts: 3.747 MB Vertex, 22.848 MB Texture ====================== ====================== Memory post level load ====================== ====================== WARN: ENGINE: Lua garbage collection starting FreeUnusedBlocksInBuckets released 0 Kb DaveD: Level loaded in 0.14 seconds Anim: anims\objects\tk_arrow_idle.jan: loaded (1 frames latency) Anim: anims\dartnew\helmet\darthelmetdn.jan: loaded (1 frames latency) Anim: anims\thought_bubble\shieldloop.jan: loaded (1 frames latency) Anim: anims\dartnew\standready.jan: loaded (1 frames latency) Anim: anims\dartnew\walkmove.jan: loaded (1 frames latency) Anim: anims\janitor\hint_end.jan: loaded (1 frames latency) Anim: anims\thought_bubble\ballstatic.jan: loaded (1 frames latency) Anim: anims\dartnew\actionfall.jan: loaded (1 frames latency) Anim: anims\dartnew\standstill.jan: loaded (1 frames latency) Anim: anims\dartnew\pack\packbounce_lf_rt.jan: loaded (1 frames latency) Anim: anims\dartnew\pack\packbounce_up_dn.jan: loaded (1 frames latency) Anim: anims\dartnew\helmet\darthelmetdefpose.jan: loaded (1 frames latency) 1: 1 (number) 1: 1 (number) STUBBED: This is probably wrong at GetDt (/home/icculus/projects/psychonauts/Source/CommonLibs/DFUtil/Profiler.cpp:181) STUBBED: set specular highlights at setSpecularEnable (/home/icculus/projects/psychonauts/Source/CommonLibs/DFGraphics/Renderer.cpp:2035) Anim: anims\dartnew\trnrtcycle.jan: loaded (1 frames latency) Anim: anims\dartnew\run.jan: loaded (1 frames latency) Anim: anims\dartnew\walk.jan: loaded (1 frames latency) Anim: anims\thought_bubble\bubbledoublejump.jan: loaded (1 frames latency) Anim: anims\dartnew\longjump.jan: loaded (1 frames latency) Anim: anims\menubrain\door1crack.jan: loaded (1 frames latency) Anim: anims\menubrain\door1crackedidle.jan: loaded (1 frames latency) Anim: anims\menubrain\door1closedidle.jan: loaded (1 frames latency) Anim: anims\dartnew\180.jan: loaded (1 frames latency) Anim: anims\menubrain\door3crack.jan: loaded (1 frames latency) Anim: anims\menubrain\door3crackedidle.jan: loaded (1 frames latency) Anim: anims\menubrain\door3closedidle.jan: loaded (1 frames latency) Anim: anims\dartnew\railslide45angle.jan: loaded (1 frames latency) Anim: anims\dartnew\railslideflat.jan: loaded (1 frames latency) Anim: anims\dartnew\trnlfcycle.jan: loaded (1 frames latency) WARN: (none(-1) SetNewAction LevelScript: no string passed Anim: anims\dartnew\mainmenu_jump.jan: loaded (1 frames latency) Anim: anims\menubrain\door1open.jan: loaded (1 frames latency) ERROR: Assert in /home/icculus/projects/psychonauts/Source/game/luatest/../../CommonLibs/Include/../DFGraphics/Color.h, line 96 v.x >= 0.0f && v.x <= 1.0f && v.y >= 0.0f && v.y <= 1.0f && v.z >= 0.0f && v.z <= 1.0f && v.w >= 0.0f && v.w <= 1.0f Encountered Error: Psychonauts has encountered an error /home/icculus/projects/psychonauts/Source/game/luatest/../../CommonLibs/Include/../DFGraphics/Color.h, line 96 v.x >= 0.0f && v.x <= 1.0f && v.y >= 0.0f && v.y <= 1.0f && v.z >= 0.0f && v.z <= 1.0f && v.w >= 0.0f && v.w <= 1.0f Please contact technical support at http://www.doublefine.com. I am currently using Bumblebee for hybrid graphics, if that helps in any way.

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  • Windows Phone 7 development: first impressions

    - by DigiMortal
    After hard week in work I got some free time to play with Windows Phone 7 CTP developer tools. Although my first test application is still unfinished I think it is good moment to share my first experiences to you. In this posting I will give you quick overview of Windows Phone 7 developer tools from developer perspective. If you are familiar with Visual Studio 2010 then you will feel comfortable because Windows Phone 7 CTP developer tools base on Visual Studio 2010 Express. Project templates There are five project templates available. Three of them are based on Silverlight and two on XNA Game Studio: Windows Phone Application (Silverlight) Windows Phone List Application (Silverlight) Windows Phone Class Library (Silverlight) Windows Phone Game (XNA Game Studio) Windows Phone Game Library (XNA Game Studio) Currently I am writing to test applications. One of them is based on Windows Phone Application and the other on Windows Phone List Application project template. After creating these projects you see the following views in Visual Studio. Windows Phone Application. Click on image to enlarge. Windows Phone List Application. Click on image to enlarge.  I suggest you to use some of these templates to get started more easily. Windows Phone 7 emulator You can run your Windows Phone 7 applications on Windows Phone 7 emulator that comes with developer tools CTP. If you run your application then emulator is started automatically and you can try out how your application works in phone-like emulator. You can see screenshot of emulator on right. Currently there is opened Windows Phone List Application as it is created by default. Click on image to enlarge it. Emulator is a little bit slow and uncomfortable but it works pretty well. This far I have caused only couple of crashes during my experiments. In these cases emulator works but Visual Studio gets stuck because it cannot communicate with emulator. One important note. Emulator is based on virtual machine although you can see only phone screen and options toolbar. If you want to run emulator you must close all virtual machines running on your machine and run Visual Studio 2010 as administrator. Once you run emulator you can keep it open because you can stop your application in Visual Studio, modify, compile and re-deploy it without restarting emulator. Designing user interfaces You can design user interface of your application in Visual Studio. When you open XAML-files it is displayed in window with two panels. Left panel shows you device screen and works as visual design environment while right panel shows you XAML mark-up and let’s you modify XML if you need it. As it is one of my very first Silverlight applications I felt more comfortable with XAML editor because property names in property boxes of visual designer confused me a little bit. Designer panel is not very good because it is visually hard to follow. It has black background that makes dark borders of controls very hard to see. If you have monitor with very high contrast then it is may be not a real problem. I have usual monitor and I have problem. :) Putting controls on design surface, dragging and resizing them is also pretty painful. Some controls are drawn correctly but for some controls you have to set width and height in XML so they can be resized. After some practicing it is not so annoying anymore. On the right you can see toolbox with some controllers. This is all you get out of the box. But it is sufficient to get started. After getting some experiences you can create your own controls or use existing ones from other vendors or developers. If it is your first time to do stuff with Silverlight then keep Google open – you need it hard. After getting over the first shock you get the point very quickly and start developing at normal speed. :) Writing source code Writing source code is the most familiar part of this action. Good old Visual Studio code editor with all nice features it has. But here you get also some surprises: The anatomy of Silverlight controls is a little bit different than the one of user controls in web and forms projects. Windows Phone 7 doesn’t run on full version of Windows (I bet it is some version of Windows CE or something like this) then there is less system classes you can use. Some familiar classes have less methods that in full version of .NET Framework and in these cases you have to write all the code by yourself or find libraries or source code from somewhere. These problems are really not so much problems than limitations and you get easily over them. Conclusion Windows Phone 7 CTP developer tools help you do a lot of things on Windows Phone 7. Although I expected better performance from tools I think that current performance is not a problem. This far my first test project is going very well and Google has answer for almost every question. Windows Phone 7 is mobile device and therefore it has less hardware resources than desktop computers. This is why toolset is so limited. The more you need memory the more slower is device and as you may guess it needs the more battery. If you are writing apps for mobile devices then make your best to get your application use as few resources as possible and act as fast as possible.

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  • Independence Day for Software Components &ndash; Loosening Coupling by Reducing Connascence

    - by Brian Schroer
    Today is Independence Day in the USA, which got me thinking about loosely-coupled “independent” software components. I was reminded of a video I bookmarked quite a while ago of Jim Weirich’s “Grand Unified Theory of Software Design” talk at MountainWest RubyConf 2009. I finally watched that video this morning. I highly recommend it. In the video, Jim talks about software connascence. The dictionary definition of connascence (con-NAY-sense) is: 1. The common birth of two or more at the same time 2. That which is born or produced with another. 3. The act of growing together. The brief Wikipedia page about Connascent Software Components says that: Two software components are connascent if a change in one would require the other to be modified in order to maintain the overall correctness of the system. Connascence is a way to characterize and reason about certain types of complexity in software systems. The term was introduced to the software world in Meilir Page-Jones’ 1996 book “What Every Programmer Should Know About Object-Oriented Design”. The middle third of that book is the author’s proposed graphical notation for describing OO designs. UML became the standard about a year later, so a revised version of the book was published in 1999 as “Fundamentals of Object-Oriented Design in UML”. Weirich says that the third part of the book, in which Page-Jones introduces the concept of connascence “is worth the price of the entire book”. (The price of the entire book, by the way, is not much – I just bought a used copy on Amazon for $1.36, so that was a pretty low-risk investment. I’m looking forward to getting the book and learning about connascence from the original source.) Meanwhile, here’s my summary of Weirich’s summary of Page-Jones writings about connascence: The stronger the form of connascence, the more difficult and costly it is to change the elements in the relationship. Some of the connascence types, ordered from weak to strong are: Connascence of Name Connascence of name is when multiple components must agree on the name of an entity. If you change the name of a method or property, then you need to change all references to that method or property. Duh. Connascence of name is unavoidable, assuming your objects are actually used. My main takeaway about connascence of name is that it emphasizes the importance of giving things good names so you don’t need to go changing them later. Connascence of Type Connascence of type is when multiple components must agree on the type of an entity. I assume this is more of a problem for languages without compilers (especially when used in apps without tests). I know it’s an issue with evil JavaScript type coercion. Connascence of Meaning Connascence of meaning is when multiple components must agree on the meaning of particular values, e.g that “1” means normal customer and “2” means preferred customer. The solution to this is to use constants or enums instead of “magic” strings or numbers, which reduces the coupling by changing the connascence form from “meaning” to “name”. Connascence of Position Connascence of positions is when multiple components must agree on the order of values. This refers to methods with multiple parameters, e.g.: eMailer.Send("[email protected]", "[email protected]", "Your order is complete", "Order completion notification"); The more parameters there are, the stronger the connascence of position is between the component and its callers. In the example above, it’s not immediately clear when reading the code which email addresses are sender and receiver, and which of the final two strings are subject vs. body. Connascence of position could be improved to connascence of type by replacing the parameter list with a struct or class. This “introduce parameter object” refactoring might be overkill for a method with 2 parameters, but would definitely be an improvement for a method with 10 parameters. This points out two “rules” of connascence:  The Rule of Degree: The acceptability of connascence is related to the degree of its occurrence. The Rule of Locality: Stronger forms of connascence are more acceptable if the elements involved are closely related. For example, positional arguments in private methods are less problematic than in public methods. Connascence of Algorithm Connascence of algorithm is when multiple components must agree on a particular algorithm. Be DRY – Don’t Repeat Yourself. If you have “cloned” code in multiple locations, refactor it into a common function.   Those are the “static” forms of connascence. There are also “dynamic” forms, including… Connascence of Execution Connascence of execution is when the order of execution of multiple components is important. Consumers of your class shouldn’t have to know that they have to call an .Initialize method before it’s safe to call a .DoSomething method. Connascence of Timing Connascence of timing is when the timing of the execution of multiple components is important. I’ll have to read up on this one when I get the book, but assume it’s largely about threading. Connascence of Identity Connascence of identity is when multiple components must reference the entity. The example Weirich gives is when you have two instances of the “Bob” Employee class and you call the .RaiseSalary method on one and then the .Pay method on the other does the payment use the updated salary?   Again, this is my summary of a summary, so please be forgiving if I misunderstood anything. Once I get/read the book, I’ll make corrections if necessary and share any other useful information I might learn.   See Also: Gregory Brown: Ruby Best Practices Issue #24: Connascence as a Software Design Metric (That link is failing at the time I write this, so I had to go to the Google cache of the page.)

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  • Using Lightbox with _Screen

    Although, I have to admit that I discovered Bernard Bout's ideas and concepts about implementing a lightbox in Visual FoxPro quite a while ago, there was no "spare" time in active projects that allowed me to have a closer look into his solution(s). Luckily, these days I received a demand to focus a little bit more on this. This article describes the steps about how to integrate and make use of Bernard's lightbox class in combination with _Screen in Visual FoxPro. The requirement in this project was to be able to visually lock the whole application (_Screen area) and guide the user to an information that should not be ignored easily. Depending on the importance any current user activity should be interrupted and focus put onto the notification. Getting the "meat", eh, source code Please check out Bernard's blog on Foxite directly in order to get the latest and greatest version. As time of writing this article I use version 6.0 as described in this blog entry: The Fastest Lightbox Ever The Lightbox class is sub-classed from the imgCanvas class from the GdiPlusX project on VFPx and therefore you need to have the source code of GdiPlusX as well, and integrate it into your development environment. The version I use is available here: Release GDIPlusX 1.20 As soon as you open the bbGdiLightbox class the first it, VFP might ask you to update the reference to the gdiplusx.vcx. As we have the sources, no problem and you have access to Bernard's code. The class itself is pretty easy to understand, some properties that you do not need to change and three methods: Setup(), ShowLightbox() and BeforeDraw() The challenge - _Screen or not? Reading Bernard's article about the fastest lightbox ever, he states the following: "The class will only work on a form. It will not support any other containers" Really? And what about _Screen? Isn't that a form class, too? Yes, of course it is but nonetheless trying to use _Screen directly will fail. Well, let's have look at the code to see why: WITH This .Left = 0 .Top = 0 .Height = ThisForm.Height .Width = ThisForm.Width .ZOrder(0) .Visible = .F.ENDWITH During the setup of the lightbox as well as while capturing the image as replacement for your forms and controls, the object reference Thisform is used. Which is a little bit restrictive to my opinion but let's continue. The second issue lies in the method ShowLightbox() and introduced by the call of .Bitmap.FromScreen(): Lparameters tlVisiblilty* tlVisiblilty - show or hide (T/F)* grab a screen dump with controlsIF tlVisiblilty Local loCaptureBmp As xfcBitmap Local lnTitleHeight, lnLeftBorder, lnTopBorder, lcImage, loImage lnTitleHeight = IIF(ThisForm.TitleBar = 1,Sysmetric(9),0) lnLeftBorder = IIF(ThisForm.BorderStyle < 2,0,Sysmetric(3)) lnTopBorder = IIF(ThisForm.BorderStyle < 2,0,Sysmetric(4)) With _Screen.System.Drawing loCaptureBmp = .Bitmap.FromScreen(ThisForm.HWnd,; lnLeftBorder,; lnTopBorder+lnTitleHeight,; ThisForm.Width ,; ThisForm.Height) ENDWITH * save it to a property This.capturebmp = loCaptureBmp ThisForm.SetAll("Visible",.F.) This.DraW() This.Visible = .T.ELSE ThisForm.SetAll("Visible",.T.) This.Visible = .F.ENDIF My first trials in using the class ended in an exception - GdiPlusError:OutOfMemory - thrown by the Bitmap object. Frankly speaking, this happened mainly because of my lack of knowledge about GdiPlusX. After reading some documentation, especially about the FromScreen() method I experimented a little bit. Capturing the visible area of _Screen actually was not the real problem but the dimensions I specified for the bitmap. The modifications - step by step First of all, it is to get rid of restrictive object references on Thisform and to change them into either This.Parent or more generic into This.oForm (even better: This.oControl). The Lightbox.Setup() method now sets the necessary object reference like so: *====================================================================* Initial setup* Default value: This.oControl = "This.Parent"* Alternative: This.oControl = "_Screen"*====================================================================With This .oControl = Evaluate(.oControl) If Vartype(.oControl) == T_OBJECT .Anchor = 0 .Left = 0 .Top = 0 .Width = .oControl.Width .Height = .oControl.Height .Anchor = 15 .ZOrder(0) .Visible = .F. EndIfEndwith Also, based on other developers' comments in Bernard articles on his lightbox concept and evolution I found the source code to handle the differences between a form and _Screen and goes into Lightbox.ShowLightbox() like this: *====================================================================* tlVisibility - show or hide (T/F)* grab a screen dump with controls*====================================================================Lparameters tlVisibility Local loControl m.loControl = This.oControl If m.tlVisibility Local loCaptureBmp As xfcBitmap Local lnTitleHeight, lnLeftBorder, lnTopBorder, lcImage, loImage lnTitleHeight = Iif(m.loControl.TitleBar = 1,Sysmetric(9),0) lnLeftBorder = Iif(m.loControl.BorderStyle < 2,0,Sysmetric(3)) lnTopBorder = Iif(m.loControl.BorderStyle < 2,0,Sysmetric(4)) With _Screen.System.Drawing If Upper(m.loControl.Name) == Upper("Screen") loCaptureBmp = .Bitmap.FromScreen(m.loControl.HWnd) Else loCaptureBmp = .Bitmap.FromScreen(m.loControl.HWnd,; lnLeftBorder,; lnTopBorder+lnTitleHeight,; m.loControl.Width ,; m.loControl.Height) EndIf Endwith * save it to a property This.CaptureBmp = loCaptureBmp m.loControl.SetAll("Visible",.F.) This.Draw() This.Visible = .T. Else This.CaptureBmp = .Null. m.loControl.SetAll("Visible",.T.) This.Visible = .F. Endif {loadposition content_adsense} Are we done? Almost... Although, Bernard says it clearly in his article: "Just drop the class on a form and call it as shown." It did not come clear to my mind in the first place with _Screen, but, yeah, he is right. Dropping the class on a form provides a permanent link between those two classes, it creates a valid This.Parent object reference. Bearing in mind that the lightbox class can not be "dropped" on the _Screen, we have to create the same type of binding during runtime execution like so: *====================================================================* Create global lightbox component*==================================================================== Local llOk, loException As Exception m.llOk = .F. m.loException = .Null. If Not Vartype(_Screen.Lightbox) == "O" Try _Screen.AddObject("Lightbox", "bbGdiLightbox") Catch To m.loException Assert .F. Message m.loException.Message EndTry EndIf m.llOk = (Vartype(_Screen.Lightbox) == "O")Return m.llOk Through runtime instantiation we create a valid binding to This.Parent in the lightbox object and the code works as expected with _Screen. Ease your life: Use properties instead of constants Having a closer look at the BeforeDraw() method might wet your appetite to simplify the code a little bit. Looking at the sample screenshots in Bernard's article you see several forms in different colors. This got me to modify the code like so: *====================================================================* Apply the actual lightbox effect on the captured bitmap.*====================================================================If Vartype(This.CaptureBmp) == T_OBJECT Local loGfx As xfcGraphics loGfx = This.oGfx With _Screen.System.Drawing loGfx.DrawImage(This.CaptureBmp,This.Rectangle,This.Rectangle,.GraphicsUnit.Pixel) * change the colours as needed here * possible colours are (220,128,0,0),(220,0,0,128) etc. loBrush = .SolidBrush.New(.Color.FromArgb( ; This.Opacity, .Color.FromRGB(This.BorderColor))) loGfx.FillRectangle(loBrush,This.Rectangle) EndwithEndif Create an additional property Opacity to specify the grade of translucency you would like to have without the need to change the code in each instance of the class. This way you only need to change the values of Opacity and BorderColor to tweak the appearance of your lightbox. This could be quite helpful to signalize different levels of importance (ie. green, yellow, orange, red, etc...) of notifications to the users of the application. Final thoughts Using the lightbox concept in combination with _Screen instead of forms is possible. Already Jim Wiggins comments in Bernard's article to loop through the _Screen.Forms collection in order to cascade the lightbox visibility to all active forms. Good idea. But honestly, I believe that instead of looping all forms one could use _Screen.SetAll("ShowLightbox", .T./.F., "Form") with Form.ShowLightbox_Access method to gain more speed. The modifications described above might provide even more features to your applications while consuming less resources and performance. Additionally, the restrictions to capture only forms does not exist anymore. Using _Screen you are able to capture and cover anything. The captured area of _Screen does not include any toolbars, docked windows, or menus. Therefore, it is advised to take this concept on a higher level and to combine it with additional classes that handle the state of toolbars, docked windows and menus. Which I did for the customer's project.

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  • Prepping a conference

    - by Laurent Bugnion
    I have had the chance to talk at many conferences these past few years, and came up with a way to prepare them which works really well for me. Most importantly, it would make it quite easy to overcome an emergency (for example if my laptop would suddenly lose data). The whole code as well as the slides and other documents are in the cloud. I also use source control for my demos, so that I always have the latest and the greatest, but also a history of changes I made to my demos. Finally I have a system of code snippets which works great, and I often had very positive remarks from the audience regarding that. Putting everything in the cloud The one thing I used to be the most scared of was a sudden crash of my laptop, and being unable to restore in time for a conference. Most conferences ask speakers to send slides a few days (or weeks…) in advance, but let's face it, we all have last minute changes to our talks and I always come in the conference with updated slides that I pass to the management team. The answer to that dilemma used to be working off memory sticks, and that worked not bad. However last year I started putting all the documents relating to a conference in a DropBox folder, and that works great too. Obviously DropBox works only if you have connectivity, so if I for instance update slides while on an international flight, I cannot save to the cloud. The obvious answer to that is to backup everything on a memory stick… but I have to admit, I have been trusting my luck and working off my laptop HD and then synching everything to the cloud after landing. Of course on some US national flights you get WiFi on board, so in that case it is even simpler :) Usually after the conference is done, I remove the files from DropBox and copy them to their "final destination". They are backed up from there to BackBlaze, the great online backup service I am using routinely (I currently have about 90GB of data in BackBlaze). Outlining the presentations I like to have a written outline of my presentations written somewhere. I keep it simple, just write the various sections of the presentation with timing. I guess it is a remnant of the time when I was a private pilot, and using checklists for flight preparation. For example: Demo about designability 15' (0:37) Switch to Blend Open MainPage.xaml Create a DataTemplate ... Here I can immediately see during the presentation if I am taking too much time for my demo (0:37 is where I need to be when I am done with this section of the presentation, and 15' is the time that this particular section takes). I keep these sections reasonable, I don't detail every step of the preparation. Typically I have one such section for every 10-15 minutes of my talks. Yes, I am timing my presentations. I keep adjusting these numbers when I rehearse, and this really helps to feel more confident during the presentations. This is especially important for presentations that are long, like my MIX11 demo which clocked at 57 minutes (I had a lot of stuff to show…). Such presentations are risky, because if anything goes wrong, you will have to cut stuff, so the answer to that is: Rehearse, rehearse and when you're done rehearsing, rehearse a little more. I also have a "Preparation" section where I outline what I need to do before a presentation. For instance: Preparation Reboot in VHD Make sure MSN and Twitter are not running. Open VS10 and load demo Open Blend and load demo Run the WP7 emulator ... I typically start preparing my laptop an hour before the talk, starting everything I need to start and then putting my laptop to sleep. Saving and printing the outline, Timing Printing is a real problem because it is really hard to find a printer at most conference venues, and also quite hard in hotels. To solve that, I simply write everything in OneNote (synched to the cloud, now you start to know what I like ;) and then I print it to a PDF (I use CutePDFWriter) that I save to my Kindle. During the presentation, I read the outline off the Kindle (I mostly just need a quick check to see how I am timing). For timing during the presentation, I use the free tool ChronoGPS on my Windows Phone 7, but of course any phone these days has a clock/chrono application. In some conferences, they even have timers that the presenters can see, but they tend to count down and I prefer to count up… so I just use my own :) Source control for demos For demos, I create a separate folder and use Mercurial as source control. Mercurial has the huge advantage (over SVN or TFS) to work offline too, so I can commit while on a plane, and all the history is saved. Then when I have connectivity I push everything to the cloud (I am using the fantastic Trunksapp.com for my private repositories). Here too the obvious downside is the risk of losing my last changes if my laptop crashes before I can push to the cloud, and here too the obvious answer would be to work from a memory stick… though I have to admit I didn't do that lately (except when I was writing Silverlight 4 Unleashed, where I was really paranoid…) And code snippets? I am one of these presenters who hates to type in front of an audience. I can type really fast (writing two books has this advantage, it really teaches you to touch type and be fast at it) but in the context of an audience, on a stage where it is often damn cold (an issue I had a lot in past conferences, air conditioning can freeze your fingers and make it really hard to type), it doesn't work as well. I don't know for you, but I really dislike seeing a presentation where the speaker uses the backspace key more often than others ;) To solve that, I like to have my code ready in snippets, and drag them to the screen. Then I can spend time explaining each code snippet, while highlighting portions of the code (always highlight what you talk about, the audience often doesn't even see the cursor and doesn't know where you are on the screen!) Over the years I have used various solutions for code snippets, and now I have one which works really well… if you take a few precautions! I use the Visual Studio Toolbox. Preparing the code snippets You can store code snippets in the Toolbox for anything, XAML, C# etc. I arrange the snippets in the order in which I need them, which is a great way to remember what comes next in the presentation. I also separate them by topic, to make it easier to find them, for example when I switch to the slides and then back to the code. Remember that no matter how experienced you are, you will feel more nervous on stage than while you are preparing, so any way to make it easier for you is going to be beneficial to the audience. To store a code snippet, I do the following: Open the final demo that you want to show to the audience in Visual Studio. In your code, select a snippet of code that you want to explain in particular. Make sure that the Visual Studio Toolbox is open (menu View, Toolbox or Ctrl-Alt-X). Drag the selected snippet from the code window to the toolbox. (if needed) drag the snippet to the correct location (for example between two other code snippets so that you can access it as you speak through the demo). Right click on the snippet and select Rename Item from the context menu. Select a meaningful name. For me I use the following conventions: If it is a method, I use the method's name. If it is not a whole method, I use a descriptive name. If it is the content of a method (i.e. the body only, without the method's signature), I use "-> MethodName". This reminds me during the presentation that this is only the body, and that I need to insert that into an existing signature. This is the case, for instance, when I use Visual Studio to automatically generate the members of an interface’s implementation; then I only need to insert my snippet inside the generated method body. Saving the snippets This is the most important!! It happened to me a few times that VS10 lost its settings. When that happens, the snippets are lost too! Yeah that really sucks, especially (as it happened once) when this is the case about an hour before a talk… Stress and sweat follows, not good conditions to start a talk in front of an audience believe me. Thankfully, saving snippets is really easy with the following steps: Select the menu Tools, Import and Export Settings. Select Export selected environment settings and press Next. Uncheck All Settings. Then expand General Settings and select Toolbox (only!). Press Next. Select your source control folder and save under a meaningful name (for instance Snippets.vssettings). Commit to source control and push to the cloud. By the way, this also has the advantage of applying source control to the snippets file (which is an XML file), so you get history for free on that file! Reimporting the snippets If VS loses its settings and you need to reimport the snippets, this can be done super easily and very fast. Make sure that the Toolbox is empty. When you import snippets, they are merged with existing ones, they do not replace the content of the Toolbox. Unless merging is really what you want, make sure that your Toolbox is clean before you import, it is really easier. Select the menu Tools, Import and Export Settings. Select Import selected environment settings and press Next. Select No, just import new settings and press Next. Press Browse and select the Snippets.vssettings file. Press Finish. Et voila, all your snippets appear again in the Toolbox. Whew, the worst was averted and you can start your demo without sweating! (I had to do that once literally 5 minutes before the start of a demo, while my laptop was already hooked to the projector, and it went just fine). What about special tools? When using special tools (for example beta versions of tools you have an early access to), or a special configuration of your laptop, things can get tricky because you cannot really be sure that you will get a laptop with the same tools and the same configuration at the conference. To solve that, I use the following precautions: I make my demos from a Virtual Hard Disk. The great John Papa made a very easy-to-follow web page where he explains how to create a VHD and install Win7 to it. This gives you the full power of your laptop (as fast as booting from the metal). For me, I have a basic configuration that I saved on a USB harddrive (Win7 plus drivers, basic settings for desktop, folder options, taskbar etc) and Visual Studio 2010 SP1 on it. When preparing, I start by copying this "basis VHD" to my laptop. I install additional tools and configurations. I save the VHD back to the USB harddrive in a different folder. This would allow me to reinstall my demo environment quite fast, for example in case of harddrive failure. Replace the harddrive, copy the VHD to it, configure the BCD and you can start. Unfortunately this only works if the laptop itself still works. In the worst case of total failure, my security is to back all the installers up: The installers I use are synched on all my laptops and backed up to BackBlaze. If the worst happens and my laptop is absolutely broken, I can download the installer from BackBlaze and install on another laptop. This of course takes some time, and if that happens 5 minutes before a presentation, well… I don't have an answer to that, except of course crossing my fingers. Still, all that gives me additional security. Conclusion Remember folks, talking to an audience, large or small, will make you nervous. Just ask Scott Hanselman :) The goal here is to create the best possible conditions for you, and to create an environment where everything is saved and easy to restore, where everything is well known and provides you with additional confidence. The cooler you feel before the presentation (and during ;)), the better your presentation will be. Here too, the goal is to provide the best user experience you can have, which in turn will make it more enjoyable for your audience! Happy presenting :) Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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  • Windows Workflow Foundation (WF) and things I wish were more intuitive

    - by pjohnson
    I've started using Windows Workflow Foundation, and so far ran into a few things that aren't incredibly obvious. Microsoft did a good job of providing a ton of samples, which is handy because you need them to get anywhere with WF. The docs are thin, so I've been bouncing between samples and downloadable labs to figure out how to implement various activities in a workflow. Code separation or not? You can create a workflow and activity in Visual Studio with or without code separation, i.e. just a .cs "Component" style object with a Designer.cs file, or a .xoml XML markup file with code behind (beside?) it. Absence any obvious advantage to one or the other, I used code separation for workflows and any complex custom activities, and without code separation for custom activities that just inherit from the Activity class and thus don't have anything special in the designer. So far, so good. Workflow Activity Library project type - What's the point of this separate project type? So far I don't see much advantage to keeping your custom activities in a separate project. I prefer to have as few projects as needed (and no fewer). The Designer's Toolbox window seems to find your custom activities just fine no matter where they are, and the debugging experience doesn't seem to be any different. Designer Properties - This is about the designer, and not specific to WF, but nevertheless something that's hindered me a lot more in WF than in Windows Forms or elsewhere. The Properties window does a good job of showing you property values when you hover the mouse over the values. But they don't do the same to find out what a control's type is. So maybe if I named all my activities "x1" and "x2" instead of helpful self-documenting names like "listenForStatusUpdate", then I could easily see enough of the type to determine what it is, but any names longer than those and all I get of the type is "System.Workflow.Act" or "System.Workflow.Compone". Even hitting the dropdown doesn't expand any wider, like the debugger quick watch "smart tag" popups do when you scroll through members. The only way I've found around this in VS 2008 is to widen the Properties dialog, losing precious designer real estate, then shrink it back down when you're done to see what you were doing. Really? WF Designer - This is about the designer, and I believe is specific to WF. I should be able to edit the XML in a .xoml file, or drag and drop using the designer. With WPF (at least in VS 2010 Ultimate), these are side by side, and changes to one instantly update the other. With WF, I have to right-click on the .xoml file, choose Open With, and pick XML Editor to edit the text. It looks like this is one way where WF didn't get the same attention WPF got during .NET Fx 3.0 development. Service - In the WF world, this is simply a class that talks to the workflow about things outside the workflow, not to be confused with how the term "service" is used in every other context I've seen in the Windows and .NET world, i.e. an executable that waits for events or requests from a client and services them (Windows service, web service, WCF service, etc.). ListenActivity - Such a great concept, yet so unintuitive. It seems you need at least two branches (EventDrivenActivity instances), one for your positive condition and one for a timeout. The positive condition has a HandleExternalEventActivity, and the timeout has a DelayActivity followed by however you want to handle the delay, e.g. a ThrowActivity. The timeout is simple enough; wiring up the HandleExternalEventActivity is where things get fun. You need to create a service (see above), and an interface for that service (this seems more complex than should be necessary--why not have activities just wire to a service directly?). And you need to create a custom EventArgs class that inherits from ExternalDataEventArgs--you can't create an ExternalDataEventArgs event handler directly, even if you don't need to add any more information to the event args, despite ExternalDataEventArgs not being marked as an abstract class, nor a compiler error nor warning nor any other indication that you're doing something wrong, until you run it and find that it always times out and get to check every place mentioned here to see why. Your interface and service need an event that consumes your custom EventArgs class, and a method to fire that event. You need to call that method from somewhere. Then you get to hope that you did everything just right, or that you can step through code in the debugger before your Delay timeout expires. Yes, it's as much fun as it sounds. TransactionScopeActivity - I had the bright idea of putting one in as a placeholder, then filling in the database updates later. That caused this error: The workflow hosting environment does not have a persistence service as required by an operation on the workflow instance "[GUID]". ...which is about as helpful as "Object reference not set to an instance of an object" and even more fun to debug. Google led me to this Microsoft Forums hit, and from there I figured out it didn't like that the activity had no children. Again, a Validator on TransactionScopeActivity would have pointed this out to me at design time, rather than handing me a nearly useless error at runtime. Easily enough, I disabled the activity and that fixed it. I still see huge potential in my work where WF could make things easier and more flexible, but there are some seriously rough edges at the moment. Maybe I'm just spoiled by how much easier and more intuitive development elsewhere in the .NET Framework is.

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  • Inside Red Gate - Be Reasonable!

    - by Simon Cooper
    As I discussed in my previous posts, divisions and project teams within Red Gate are allowed a lot of autonomy to manage themselves. It's not just the teams though, there's an awful lot of freedom given to individual employees within the company as well. Reasonableness How Red Gate treats it's employees is embodied in the phrase 'You will be reasonable with us, and we will be reasonable with you'. As an employee, you are trusted to do your job to the best of you ability. There's no one looking over your shoulder, no one clocking you in and out each day. Everyone is working at the company because they want to, and one of the core ideas of Red Gate is that the company exists to 'let people do the best work of their lives'. Everything is geared towards that. To help you do your job, office services and the IT department are there. If you need something to help you work better (a third or fourth monitor, footrests, or a new keyboard) then ask people in Information Systems (IS) or Office Services and you will be given it, no questions asked. Everyone has administrator access to their own machines, and you can install whatever you want on it. If there's a particular bit of software you need, then ask IS and they will buy it. As an example, last year I wanted to replace my main hard drive with an SSD; I had a summer job at school working in a computer repair shop, so knew what to do. I went to IS and asked for 'an SSD, a SATA cable, and a screwdriver'. And I got it there and then, even the screwdriver. Awesome. I screwed it in myself, copied all my main drive files across, and I was good to go. Of course, if you're not happy doing that yourself, then IS will sort it all out for you, no problems. If you need something that the company doesn't have (say, a book off Amazon, or you need some specifications printing off & bound), then everyone has a expense limit of £100 that you can use without any sign-off needed from your managers. If you need a company credit card for whatever reason, then you can get it. This freedom extends to working hours and holiday; you're expected to be in the office 11am-3pm each day, but outside those times you can work whenever you want. If you need a half-day holiday on a days notice, or even the same day, then you'll get it, unless there's a good reason you're needed that day. If you need to work from home for a day or so for whatever reason, then you can. If it's reasonable, then it's allowed. Trust issues? A lot of trust, and a lot of leeway, is given to all the people in Red Gate. Everyone is expected to work hard, do their jobs to the best of their ability, and there will be a minimum of bureaucratic obstacles that stop you doing your work. What happens if you abuse this trust? Well, an example is company trip expenses. You're free to expense what you like; food, drink, transport, etc, but if you expenses are not reasonable, then you will never travel with the company again. Simple as that. Everyone knows when they're abusing the system, so simply don't do it. Along with reasonableness, another phrase used is 'Don't be a ***'. If you act like a ***, and abuse any of the trust placed in you, even if you're the best tester, salesperson, dev, or manager in the company, then you won't be a part of the company any more. From what I know about other companies, employee trust is highly variable between companies, all the way up to CCTV trained on employee's monitors. As a dev, I want to produce well-written & useful code that solves people's problems. Being able to get whatever I need - install whatever tools I need, get time off when I need to, obtain reference books within a day - all let me do my job, and so let Red Gate help other people do their own jobs through the tools we produce. Plus, I don't think I would like working for a company that doesn't allow admin access to your own machine and blocks Facebook!

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  • NoSQL Java API for MySQL Cluster: Questions & Answers

    - by Mat Keep
    The MySQL Cluster engineering team recently ran a live webinar, available now on-demand demonstrating the ClusterJ and ClusterJPA NoSQL APIs for MySQL Cluster, and how these can be used in building real-time, high scale Java-based services that require continuous availability. Attendees asked a number of great questions during the webinar, and I thought it would be useful to share those here, so others are also able to learn more about the Java NoSQL APIs. First, a little bit about why we developed these APIs and why they are interesting to Java developers. ClusterJ and Cluster JPA ClusterJ is a Java interface to MySQL Cluster that provides either a static or dynamic domain object model, similar to the data model used by JDO, JPA, and Hibernate. A simple API gives users extremely high performance for common operations: insert, delete, update, and query. ClusterJPA works with ClusterJ to extend functionality, including - Persistent classes - Relationships - Joins in queries - Lazy loading - Table and index creation from object model By eliminating data transformations via SQL, users get lower data access latency and higher throughput. In addition, Java developers have a more natural programming method to directly manage their data, with a complete, feature-rich solution for Object/Relational Mapping. As a result, the development of Java applications is simplified with faster development cycles resulting in accelerated time to market for new services. MySQL Cluster offers multiple NoSQL APIs alongside Java: - Memcached for a persistent, high performance, write-scalable Key/Value store, - HTTP/REST via an Apache module - C++ via the NDB API for the lowest absolute latency. Developers can use SQL as well as NoSQL APIs for access to the same data set via multiple query patterns – from simple Primary Key lookups or inserts to complex cross-shard JOINs using Adaptive Query Localization Marrying NoSQL and SQL access to an ACID-compliant database offers developers a number of benefits. MySQL Cluster’s distributed, shared-nothing architecture with auto-sharding and real time performance makes it a great fit for workloads requiring high volume OLTP. Users also get the added flexibility of being able to run real-time analytics across the same OLTP data set for real-time business insight. OK – hopefully you now have a better idea of why ClusterJ and JPA are available. Now, for the Q&A. Q & A Q. Why would I use Connector/J vs. ClusterJ? A. Partly it's a question of whether you prefer to work with SQL (Connector/J) or objects (ClusterJ). Performance of ClusterJ will be better as there is no need to pass through the MySQL Server. A ClusterJ operation can only act on a single table (e.g. no joins) - ClusterJPA extends that capability Q. Can I mix different APIs (ie ClusterJ, Connector/J) in our application for different query types? A. Yes. You can mix and match all of the API types, SQL, JDBC, ODBC, ClusterJ, Memcached, REST, C++. They all access the exact same data in the data nodes. Update through one API and new data is instantly visible to all of the others. Q. How many TCP connections would a SessionFactory instance create for a cluster of 8 data nodes? A. SessionFactory has a connection to the mgmd (management node) but otherwise is just a vehicle to create Sessions. Without using connection pooling, a SessionFactory will have one connection open with each data node. Using optional connection pooling allows multiple connections from the SessionFactory to increase throughput. Q. Can you give details of how Cluster J optimizes sharding to enhance performance of distributed query processing? A. Each data node in a cluster runs a Transaction Coordinator (TC), which begins and ends the transaction, but also serves as a resource to operate on the result rows. While an API node (such as a ClusterJ process) can send queries to any TC/data node, there are performance gains if the TC is where most of the result data is stored. ClusterJ computes the shard (partition) key to choose the data node where the row resides as the TC. Q. What happens if we perform two primary key lookups within the same transaction? Are they sent to the data node in one transaction? A. ClusterJ will send identical PK lookups to the same data node. Q. How is distributed query processing handled by MySQL Cluster ? A. If the data is split between data nodes then all of the information will be transparently combined and passed back to the application. The session will connect to a data node - typically by hashing the primary key - which then interacts with its neighboring nodes to collect the data needed to fulfil the query. Q. Can I use Foreign Keys with MySQL Cluster A. Support for Foreign Keys is included in the MySQL Cluster 7.3 Early Access release Summary The NoSQL Java APIs are packaged with MySQL Cluster, available for download here so feel free to take them for a spin today! Key Resources MySQL Cluster on-line demo  MySQL ClusterJ and JPA On-demand webinar  MySQL ClusterJ and JPA documentation MySQL ClusterJ and JPA whitepaper and tutorial

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