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• Is unit testing development or testing?

  - by Rubio

  I had a discussion with a testing manager about the role of unit and integration testing. She requested that developers report what they have unit and integration tested and how. My perspective is that unit and integration testing are part of the development process, not the testing process. Beyond semantics what I mean is that unit and integration tests should not be included in the testing reports and systems testers should not be concerned about them. My reasoning is based on two things. Unit and integration tests are planned and performed against an interface and a contract, always. Regardless of whether you use formalized contracts you still test what e.g. a method is supposed to do, i.e. a contract. In integration testing you test the interface between two distinct modules. The interface and the contract determine when the test passes. But you always test a limited part of the whole system. Systems testing on the other hand is planned and performed against the system specifications. The spec determines when the test passes. I don't see any value in communicating the breadth and depth of unit and integration tests to the (systems) tester. Suppose I write a report that lists what kind of unit tests are performed on a particular business layer class. What is he/she supposed to take away from that? Judging what should and shouldn't be tested from that is a false conclusion because the system may still not function the way the specs require even though all unit and integration tests pass. This might seem like useless academic discussion but if you work in a strictly formal environment as I do, it's actually important in determining how we do things. Anyway, am I totally wrong? (Sorry for the long post.)

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• 45 minutes to talk about C# [closed]

  - by Philip

  I have the opportunity to give a 45 minute talk on C# in the theory of programming languages class I'm taking. The college teaches Java almost exclusively, so that's what all the students are most familiar with. (There's a little C, assembly, Prolog and LISP as well.) I decide what to talk about. It seems to me the best approach is to focus on a few of the big, obvious differences between C# and Java. I don't intend it to be a recommendation to use C# -- there are reasons to use each, mostly because of their ecosystems. So I want to focus on C# as a language. I don't want to go too fast and end up listing a whole bunch of features without showing their usefulness. My current plan is this: Functions as first class objects. This is, in my opinion, one of the biggest differences between C# and Java. The professor briefly mentioned this notion and showed a LISP example, but many of the students have probably never used it. I can show real world examples where it's made my code more readable. Lambda expressions as concise syntax for anonymous functions. Obviously with examples to show how this is useful. The real hit-home examples will be at the end when it's combined with the rest. I don't see an advantage to first showing the old delegate syntax and then replacing it with lambdas -- most of us won't have ever seen delegates anyway so it would just be confusing. The yield keyword and how it's different from returning an array. I have the impression that a lot of C# developers aren't familiar with how to use this. It will likely be very foreign to Java developers. I have some examples from my own work where it was really useful, such as iterating over a tree traversal, or iterating over neighbors in a graph where the neighbors aren't stored in memory. In both cases, doing it in Java would likely mean returning a complete list -- with yield I can stop iterating if I find what I want early on, without using memory for superfluous lists or arrays. Extension methods as a way to write implementation on interfaces. We'll all be familiar with how interfaces don't allow method implementation, and how this leads to code duplication. I'll show a specific example of this and how the extension method can solve the problem. Demonstrate how the above can be combined by implementing some simple Linq methods and using them. Where, Select, First, maybe more depending on how much time is left. Ideas on which ones might 'hit home' the best? There are other things I could talk about such as generics, value types, properties and more. I haven't yet though of good ways to incorporate these. In the case of generics and value types, the advantages might not be obvious or as relevant. Properties are obviously useful, particularly since we're taught strict JavaBeans here, but I don't know if I could integrate it with the "path to Linq" discussion above without it feeling tacked on. So I'm looking for thoughts on how to talk about C#, and what to talk about. Even minor details. I'm sure there are more experienced C# developers than me here who have good insight about what's really important in the language, and what would miss the point.

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• NetworkManager broken after upgrade to Kubuntu Saucy

  - by queueoverflow

  I had Kubuntu 13.04 on my ThinkPad X220, and I upgraded to 13.10 and I am not able to connect to a wired or wireless connection. The new network tray icon does not show any entries at all. In the menu of the tray icon, there is an error saying: Require NetworkManager 0.9.8, found . I then tried the following: nmcli con ** (process:3695): WARNING **: Could not initialize NMClient /org/freedesktop/NetworkManager: Rejected send message, 3 matched rules; type="method_call", sender=":1.64" (uid=1000 pid=3695 comm="nmcli con ") interface="org.freedesktop.DBus.Properties" member="GetAll" error name="(unset)" requested_reply="0" destination="org.freedesktop.NetworkManager" (uid=0 pid=1116 comm="NetworkManager ") Error: nmcli (0.9.8.0) and NetworkManager (unknown) versions don't match. Force execution using --nocheck, but the results are unpredictable. nmcli dev ** (process:3700): WARNING **: Could not initialize NMClient /org/freedesktop/NetworkManager: Rejected send message, 3 matched rules; type="method_call", sender=":1.65" (uid=1000 pid=3700 comm="nmcli dev ") interface="org.freedesktop.DBus.Properties" member="GetAll" error name="(unset)" requested_reply="0" destination="org.freedesktop.NetworkManager" (uid=0 pid=1116 comm="NetworkManager ") Error: nmcli (0.9.8.0) and NetworkManager (unknown) versions don't match. Force execution using --nocheck, but the results are unpredictable. nm-tool ** (process:3705): WARNING **: Could not initialize NMClient /org/freedesktop/NetworkManager: Rejected send message, 3 matched rules; type="method_call", sender=":1.66" (uid=1000 pid=3705 comm="nm-tool ") interface="org.freedesktop.DBus.Properties" member="GetAll" error name="(unset)" requested_reply="0" destination="org.freedesktop.NetworkManager" (uid=0 pid=1116 comm="NetworkManager ") NetworkManager Tool State: unknown ** (process:3705): WARNING **: error: could not connect to NetworkManager Running those as root works, however. I was also able to run nmcli con up id DHCP which got my DHCP connection working and giving me internet access. That did not work using a Wifi connection though, and I do need those. How can I get networking back to work without a reinstall?

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• JPedal Action for Converting PDF to JavaFX

  - by Geertjan

  The question of the day comes from Mark Stephens, from JPedal (JPedal is the leading 100% Java PDF library, providing a Java PDF viewer, PDF to image conversion, PDF printing or adding PDF search and PDF extraction features), in the form of a screenshot: The question is clear. By looking at the annotations above, you can see that Mark has an ActionListener that has been bound to the right-click popup menu on PDF files. Now he needs to get hold of the file to which the Action has been bound. How, oh  how, can one get hold of that file? Well, it's simple. Leave everything you see above exactly as it is but change the Java code section to this: public final class PDF2JavaFXContext implements ActionListener {     private final DataObject context;     public PDF2JavaFXContext(DataObject context) {         this.context = context;     }     public void actionPerformed(ActionEvent ev) {         FileObject fo = context.getPrimaryFile();         File theFile = FileUtil.toFile(fo);         //do something with your file...     } } The point is that the annotations at the top of the class bind the Action to either Actions.alwaysEnabled, which is a factory method for creating always-enabled Actions, or Actions.context, which is a factory method for creating context-sensitive Actions. How does the Action get bound to the factory method? The annotations are converted, when the module is compiled, into XML registration entries in the "generated-layer.xml", which you can find in your "build" folder, in the Files window, after building the module. In Mark's case, since the Action should be context-sensitive to PDF files, he needs to bind his PDF2JavaFXContext ActionListener (which should probably be named "PDF2JavaFXActionListener", since the class is an ActionListener) to Actions.context. All he needs to do that is pass in the object he wants to work with into the constructor of the ActionListener. Now, when the module is built, the annotation processor is going to take the annotations and convert them to XML registration entries, but the constructor will also be checked to see whether it is empty or not. In this case, the constructor isn't empty, hence the Action should be context-sensitive and so the ActionListener is bound to Actions.context. The Actions.context will do all the enablement work for Mark, so that he will not need to provide any code for enabling/disabling the Action. The Action will be enabled whenever a DataObject is selected. Since his Action is bound to Nodes in the Projects window that represent PDF files, the Action will always be enabled whenever Mark right-clicks on a PDF Node, since the Node exposes its own DataObject. Once Mark has access to the DataObject, he can get the underlying FileObject via getPrimaryFile and he can then convert the FileObject to a java.io.File via FileUtil.getConfigFile. Once he's got the java.io.File, he can do with it whatever he needs. Further reading: http://bits.netbeans.org/dev/javadoc/

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• Organising data access for dependency injection

  - by IanAWP

  In our company we have a relatively long history of database backed applications, but have only just begun experimenting with dependency injection. I am looking for advice about how to convert our existing data access pattern into one more suited for dependency injection. Some specific questions: Do you create one access object per table (Given that a table represents an entity collection)? One interface per table? All of these would need the low level Data Access object to be injected, right? What about if there are dozens of tables, wouldn't that make the composition root into a nightmare? Would you instead have a single interface that defines things like GetCustomer(), GetOrder(), etc? If I took the example of EntityFramework, then I would have one Container that exposes an object for each table, but that container doesn't conform to any interface itself, so doesn't seem like it's compatible with DI. What we do now, in case it helps: The way we normally manage data access is through a generic data layer which exposes CRUD/Transaction capabilities and has provider specific subclasses which handle the creation of IDbConnection, IDbCommand, etc. Actual table access uses Table classes that perform the CRUD operations associated with a particular table and accept/return domain objects that the rest of the system deals with. These table classes expose only static methods, and utilise a static DataAccess singleton instantiated from a config file.

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• Mind Reading with the Raspberry Pi

  - by speakjava

  Mind Reading With The Raspberry Pi At JavaOne in San Francisco I did a session entitled "Do You Like Coffee with Your Dessert? Java and the Raspberry Pi".  As part of this I showed some demonstrations of things I'd done using Java on the Raspberry Pi.  This is the first part of a series of blog entries that will cover all the different aspects of these demonstrations. A while ago I had bought a MindWave headset from Neurosky.  I was particularly interested to see how this worked as I had had the opportunity to visit Neurosky several years ago when they were still developing this technology.  At that time the 'headset' consisted of a headband (very much in the Bjorn Borg style) with a sensor attached and some wiring that clearly wasn't quite production ready.  The commercial version is very simple and easy to use: there are two sensors, one which rests on the skin of your forehead, the other is a small clip that attaches to your earlobe. Typical EEG sensors used in hospitals require lots of sensors and they all need copious amounts of conductive gel to ensure the electrical signals are picked up.  Part of Neurosky's innovation is the development of this simple dry-sensor technology.  Having put on the sensor and turned it on (it powers off a single AAA size battery) it collects data and transmits it to a USB dongle plugged into a PC, or in my case a Raspberry Pi. From a hacking perspective the USB dongle is ideal because it does not require any special drivers for any complex, low level USB communication.  Instead it appears as a simple serial device, which on the Raspberry Pi is accessed as /dev/ttyUSB0.  Neurosky have published details of the command protocol.  In addition, the MindSet protocol document, including sample code for parsing the data from the headset, can be found here. To get everything working on the Raspberry Pi using Java the first thing was to get serial communications going.  Back in the dim distant past there was the Java Comm API.  Sadly this has grown a bit dusty over the years, but there is a more modern open source project that provides compatible and enhanced functionality, RXTXComm.  This can be installed easily on the Pi using sudo apt-get install librxtx-java.  Next I wrote a library that would send commands to the MindWave headset via the serial port dongle and read back data being sent from the headset.  The design is pretty simple, I used an event based system so that code using the library could register listeners for different types of events from the headset.  You can download a complete NetBeans project for this here.  This includes javadoc API documentation that should make it obvious how to use it (incidentally, this will work on platforms other than Linux.  I've tested it on Windows without any issues, just by changing the device name to something like COM4). To test this I wrote a simple application that would connect to the headset and then print the attention and meditation values as they were received from the headset.  Again, you can download the NetBeans project for that here. Oracle recently released a developer preview of JavaFX on ARM which will run on the Raspberry Pi.  I thought it would be cool to write a graphical front end for the MindWave data that could take advantage of the built in charts of JavaFX.  Yet another NetBeans project is available here.  Screen shots of the app, which uses a very nice dial from the JFxtras project, are shown below. I probably should add labels for the EEG data so the user knows which is the low alpha, mid gamma waves and so on.  Given that I'm not a neurologist I suspect that it won't increase my understanding of what the (rather random looking) traces mean. In the next blog I'll explain how I connected a LEGO motor to the GPIO pins on the Raspberry Pi and then used my mind to control the motor!

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• Have to run sudo dhclient eth0 automatically every boot

  - by Fyksen

  I just installed ubuntu 12.04.1 alternative install (for raid 0 on some disks). I Have some problems with the net. I'm at school, we use cable, and it got IPv6. If I run ifconfig eth0 heres my output: eth0 Link encap:Ethernet HWaddr e0:cb:4e:87:ff:db inet addr:128.39.194.217 Bcast:128.39.194.223 Mask:255.255.255.224 inet6 addr: 2001:700:1100:8008:e2cb:4eff:fe87:ffdb/64 Scope:Global inet6 addr: fe80::e2cb:4eff:fe87:ffdb/64 Scope:Link inet6 addr: 2001:700:1100:8008:48f7:c23:1d87:da6c/64 Scope:Global UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:1063378 errors:0 dropped:0 overruns:0 frame:0 TX packets:489811 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1577173461 (1.5 GB) TX bytes:37043669 (37.0 MB) Interrupt:68 Base address:0x6000 My /etc/network/interfaces look like this: # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). # The loopback network interface auto lo iface lo inet loopback # The primary network interface auto eth0 # NetworkManager#iface eth0 inet dhcp # NetworkManager#hostname 2001:700:1100:1::4 # This is an autoconfigured IPv6 interface iface eth0 inet6 auto (I had to remove the hash tags, because of the BIGFONT i get on ask ubuntu) The "network manager" says that I'm not connected. Let me know if you need any more information. :)

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• MyMessageBox for Phone and Store apps

  - by Daniel Moth

  I am sharing a class I use for both my Windows Phone 8 and Windows Store app projects. Background and my requirements For my Windows Phone 7 projects two years ago I wrote an improved custom MessageBox class that preserves the well-known MessageBox interface while offering several advantages. I documented those and shared it for Windows Phone 7 here: Guide.BeginShowMessageBox wrapper. Aside: With Windows Phone 8 we can now use the async/await feature out of the box without taking a dependency on additional/separate pre-release software. As I try to share code between my existing Windows Phone 8 projects and my new Windows Store app projects, I wanted to preserve the calling code, so I decided to wrap the WinRT MessageDialog class in a custom class to present the same MessageBox interface to my codebase. BUT. The MessageDialog class has to be called with the await keyword preceding it (which as we know is viral) which means all my calling code will also have to use await. Which in turn means that I have to change my MessageBox wrapper to present the same interface to the shared codebase and be callable with await… for both Windows Phone projects and Windows Store app projects. Solution The solution is what the requirements above outlined: a single code file with a MessageBox class that you can drop in your project, regardless of whether it targets Windows Phone 8, or Windows 8 Store apps or both. Just call any of its static Show functions using await and dependent on the overload check the return type to see which button the user chose.// example from http://www.danielmoth.com/Blog/GuideBeginShowMessageBox-Wrapper.aspx if (await MyMessageBox.Show("my message", "my caption", "ok, got it", "that sucks") == MyMessageBoxResult.Button1) { // Do something Debug.WriteLine("OK"); } The class can be downloaded from the bottom of my older blog post. Comments about this post by Daniel Moth welcome at the original blog.

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• Centrino Wireless-N 1000 takes forever to connect and keeps asking for password

  - by waclock

  A few days ago I started having this problem. When I tried to connect to any WiFi Connection it would stay connecting forever, and after a minute or so it would ask me for the password again. The strange thing is that this happened out of nowhere, I did not install any new drivers or anything like that. After this happened I decided to uninstall ubuntu and install it again ("inside windows") but the problem is still there. Any suggestions would be greatly appreciated. 0: hp-wifi: Wireless LAN Soft blocked: no Hard blocked: no 1: hp-bluetooth: Bluetooth Soft blocked: yes Hard blocked: no 2: phy0: Wireless LAN Soft blocked: no Hard blocked: no description: Ethernet interface product: RTL8111/8168B PCI Express Gigabit Ethernet controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:07:00.0 logical name: eth0 version: 06 serial: 2c:27:d7:aa:e4:7d size: 10Mbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=half firmware=rtl8168e-3_0.0.4 03/27/12 latency=0 link=no multicast=yes port=MII speed=10Mbit/s resources: irq:50 ioport:4000(size=256) memory:c0404000-c0404fff memory:c0400000-c0403fff *-network description: Wireless interface product: Centrino Wireless-N 1000 vendor: Intel Corporation physical id: 0 bus info: pci@0000:0d:00.0 logical name: wlan0 version: 00 serial: 00:1e:64:09:9c:58 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=iwlwifi driverversion=3.2.0-23-generic-pae firmware=39.31.5.1 build 35138 latency=0 link=no multicast=yes wireless=IEEE 802.11bgn resources: irq:52 memory:c4500000-c4501fff *-network description: Ethernet interface physical id: 1 bus info: usb@2:1.2 logical name: eth1 serial: ee:85:2f:7d:80:96 capabilities: ethernet physical configuration: broadcast=yes driver=ipheth ip=172.20.10.2 link=yes multicast=yes

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• ASMLib

  - by wcoekaer

  Oracle ASMlib on Linux has been a topic of discussion a number of times since it was released way back when in 2004. There is a lot of confusion around it and certainly a lot of misinformation out there for no good reason. Let me try to give a bit of history around Oracle ASMLib. Oracle ASMLib was introduced at the time Oracle released Oracle Database 10g R1. 10gR1 introduced a very cool important new features called Oracle ASM (Automatic Storage Management). A very simplistic description would be that this is a very sophisticated volume manager for Oracle data. Give your devices directly to the ASM instance and we manage the storage for you, clustered, highly available, redundant, performance, etc, etc... We recommend using Oracle ASM for all database deployments, single instance or clustered (RAC). The ASM instance manages the storage and every Oracle server process opens and operates on the storage devices like it would open and operate on regular datafiles or raw devices. So by default since 10gR1 up to today, we do not interact differently with ASM managed block devices than we did before with a datafile being mapped to a raw device. All of this is without ASMLib, so ignore that one for now. Standard Oracle on any platform that we support (Linux, Windows, Solaris, AIX, ...) does it the exact same way. You start an ASM instance, it handles storage management, all the database instances use and open that storage and read/write from/to it. There are no extra pieces of software needed, including on Linux. ASM is fully functional and selfcontained without any other components. In order for the admin to provide a raw device to ASM or to the database, it has to have persistent device naming. If you booted up a server where a raw disk was named /dev/sdf and you give it to ASM (or even just creating a tablespace without asm on that device with datafile '/dev/sdf') and next time you boot up and that device is now /dev/sdg, you end up with an error. Just like you can't just change datafile names, you can't change device filenames without telling the database, or ASM. persistent device naming on Linux, especially back in those days ways to say it bluntly, a nightmare. In fact there were a number of issues (dating back to 2004) : Linux async IO wasn't pretty persistent device naming including permissions (had to be owned by oracle and the dba group) was very, very difficult to manage system resource usage in terms of open file descriptors So given the above, we tried to find a way to make this easier on the admins, in many ways, similar to why we started working on OCFS a few years earlier - how can we make life easier for the admins on Linux. A feature of Oracle ASM is the ability for third parties to write an extension using what's called ASMLib. It is possible for any third party OS or storage vendor to write a library using a specific Oracle defined interface that gets used by the ASM instance and by the database instance when available. This interface offered 2 components : Define an IO interface - allow any IO to the devices to go through ASMLib Define device discovery - implement an external way of discovering, labeling devices to provide to ASM and the Oracle database instance This is similar to a library that a number of companies have implemented over many years called libODM (Oracle Disk Manager). ODM was specified many years before we introduced ASM and allowed third party vendors to implement their own IO routines so that the database would use this library if installed and make use of the library open/read/write/close,.. routines instead of the standard OS interfaces. PolyServe back in the day used this to optimize their storage solution, Veritas used (and I believe still uses) this for their filesystem. It basically allowed, in particular, filesystem vendors to write libraries that could optimize access to their storage or filesystem.. so ASMLib was not something new, it was basically based on the same model. You have libodm for just database access, you have libasm for asm/database access. Since this library interface existed, we decided to do a reference implementation on Linux. We wrote an ASMLib for Linux that could be used on any Linux platform and other vendors could see how this worked and potentially implement their own solution. As I mentioned earlier, ASMLib and ODMLib are libraries for third party extensions. ASMLib for Linux, since it was a reference implementation implemented both interfaces, the storage discovery part and the IO part. There are 2 components : Oracle ASMLib - the userspace library with config tools (a shared object and some scripts) oracleasm.ko - a kernel module that implements the asm device for /dev/oracleasm/* The userspace library is a binary-only module since it links with and contains Oracle header files but is generic, we only have one asm library for the various Linux platforms. This library is opened by Oracle ASM and by Oracle database processes and this library interacts with the OS through the asm device (/dev/asm). It can install on Oracle Linux, on SuSE SLES, on Red Hat RHEL,.. The library itself doesn't actually care much about the OS version, the kernel module and device cares. The support tools are simple scripts that allow the admin to label devices and scan for disks and devices. This way you can say create an ASM disk label foo on, currently /dev/sdf... So if /dev/sdf disappears and next time is /dev/sdg, we just scan for the label foo and we discover it as /dev/sdg and life goes on without any worry. Also, when the database needs access to the device, we don't have to worry about file permissions or anything it will be taken care of. So it's a convenience thing. The kernel module oracleasm.ko is a Linux kernel module/device driver. It implements a device /dev/oracleasm/* and any and all IO goes through ASMLib - /dev/oracleasm. This kernel module is obviously a very specific Oracle related device driver but it was released under the GPL v2 so anyone could easily build it for their Linux distribution kernels. Advantages for using ASMLib : A good async IO interface for the database, the entire IO interface is based on an optimal ASYNC model for performance A single file descriptor per Oracle process, not one per device or datafile per process reducing # of open filehandles overhead Device scanning and labeling built-in so you do not have to worry about messing with udev or devlabel, permissions or the likes which can be very complex and error prone. Just like with OCFS and OCFS2, each kernel version (major or minor) has to get a new version of the device drivers. We started out building the oracleasm kernel module rpms for many distributions, SLES (in fact in the early days still even for this thing called United Linux) and RHEL. The driver didn't make sense to get pushed into upstream Linux because it's unique and specific to the Oracle database. As it takes a huge effort in terms of build infrastructure and QA and release management to build kernel modules for every architecture, every linux distribution and every major and minor version we worked with the vendors to get them to add this tiny kernel module to their infrastructure. (60k source code file). The folks at SuSE understood this was good for them and their customers and us and added it to SLES. So every build coming from SuSE for SLES contains the oracleasm.ko module. We weren't as successful with other vendors so for quite some time we continued to build it for RHEL and of course as we introduced Oracle Linux end of 2006 also for Oracle Linux. With Oracle Linux it became easy for us because we just added the code to our build system and as we churned out Oracle Linux kernels whether it was for a public release or for customers that needed a one off fix where they also used asmlib, we didn't have to do any extra work it was just all nicely integrated. With the introduction of Oracle Linux's Unbreakable Enterprise Kernel and our interest in being able to exploit ASMLib more, we started working on a very exciting project called Data Integrity. Oracle (Martin Petersen in particular) worked for many years with the T10 standards committee and storage vendors and implemented Linux kernel support for DIF/DIX, data protection in the Linux kernel, note to those that wonder, yes it's all in mainline Linux and under the GPL. This basically gave us all the features in the Linux kernel to checksum a data block, send it to the storage adapter, which can then validate that block and checksum in firmware before it sends it over the wire to the storage array, which can then do another checksum and to the actual DISK which does a final validation before writing the block to the physical media. So what was missing was the ability for a userspace application (read: Oracle RDBMS) to write a block which then has a checksum and validation all the way down to the disk. application to disk. Because we have ASMLib we had an entry into the Linux kernel and Martin added support in ASMLib (kernel driver + userspace) for this functionality. Now, this is all based on relatively current Linux kernels, the oracleasm kernel module depends on the main kernel to have support for it so we can make use of it. Thanks to UEK and us having the ability to ship a more modern, current version of the Linux kernel we were able to introduce this feature into ASMLib for Linux from Oracle. This combined with the fact that we build the asm kernel module when we build every single UEK kernel allowed us to continue improving ASMLib and provide it to our customers. So today, we (Oracle) provide Oracle ASMLib for Oracle Linux and in particular on the Unbreakable Enterprise Kernel. We did the build/testing/delivery of ASMLib for RHEL until RHEL5 but since RHEL6 decided that it was too much effort for us to also maintain all the build and test environments for RHEL and we did not have the ability to use the latest kernel features to introduce the Data Integrity features and we didn't want to end up with multiple versions of asmlib as maintained by us. SuSE SLES still builds and comes with the oracleasm module and they do all the work and RHAT it certainly welcome to do the same. They don't have to rebuild the userspace library, it's really about the kernel module. And finally to re-iterate a few important things : Oracle ASM does not in any way require ASMLib to function completely. ASMlib is a small set of extensions, in particular to make device management easier but there are no extra features exposed through Oracle ASM with ASMLib enabled or disabled. Often customers confuse ASMLib with ASM. again, ASM exists on every Oracle supported OS and on every supported Linux OS, SLES, RHEL, OL withoutASMLib Oracle ASMLib userspace is available for OTN and the kernel module is shipped along with OL/UEK for every build and by SuSE for SLES for every of their builds ASMLib kernel module was built by us for RHEL4 and RHEL5 but we do not build it for RHEL6, nor for the OL6 RHCK kernel. Only for UEK ASMLib for Linux is/was a reference implementation for any third party vendor to be able to offer, if they want to, their own version for their own OS or storage ASMLib as provided by Oracle for Linux continues to be enhanced and evolve and for the kernel module we use UEK as the base OS kernel hope this helps.

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• Working with multiple interfaces on a single mock.

  - by mehfuzh

  Today , I will cover a very simple topic, which can be useful in cases we want to mock different interfaces on our expected mock object.  Our target interface is simple and it looks like:   public interface IFoo : IDisposable {     void Do(); } Now, as we can see that our target interface has implemented IDisposable and in normal cases if we have to implement it in class where language rules require use to implement that as well[no doubt about it] and whether or not there can be more complex cases, we want to ensure that rather having an extra call(..As()) or constructs to prepare it for us, we should do it in the simplest way possible. Therefore, keeping that in mind, first we create a mock of IFoo var foo = Mock.Create<IFooDispose>(); Then, as we are interested with IDisposable, we simply do: var iDisposable = foo as IDisposable;   Finally, we proceed with our existing mock code. Considering the current context, we I will check if the dispose method has invoked our mock code successfully.   bool called = false;   Mock.Arrange(() => iDisposable.Dispose()).DoInstead(() => called = true);     iDisposable.Dispose();   Assert.True(called);   Further, we assert our expectation as follows: Mock.Assert(() => iDisposable.Dispose(), Occurs.Once());   Hopefully that will help a bit and stay tuned. Enjoy!!

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• Why Wouldn't Root Be Able to Change a Zone's IP Address in Oracle Solaris 11?

  - by rickramsey

  You might assume that if you have root access to an Oracle Solaris zone, you'd be able to change the root's IP address. If so, you'd proceed along these lines ... First, you'd log in: root@global_zone:~# zlogin user-zone Then you'd remove the IP interface: root@user-zone:~# ipadm delete-ip vnic0 Next, you'd create a new IP interface: root@user-zone:~# ipadm create-ip vnic0 Then you'd assign the IP interface a new IP address (10.0.0.10): root@user-zone:~# ipadm create-addr -a local=10.0.0.10/24 vnic0/v4 ipadm: cannot create address: Permission denied Why would that happen? Here are some potential reasons: You're in the wrong zone Nobody bothered to tell you that you were fired last week. The sysadmin for the global zone (probably your ex-girlfriend) enabled link protection mode on the zone with this sweet little command: root@global_zone:~# dladm set-linkprop -p \ protection=mac-nospoof,restricted,ip-nospoof vnic0 How'd your ex-girlfriend learn to do that? By reading this article: Securing a Cloud-Based Data Center with Oracle Solaris 11 by Orgad Kimchi, Ron Larson, and Richard Friedman When you build a private cloud, you need to protect sensitive data not only while it's in storage, but also during transmission between servers and clients, and when it's being used by an application. When a project is completed, the cloud must securely delete sensitive data and make sure the original data is kept secure. These are just some of the many security precautions a sysadmin needs to take to secure data in a cloud infrastructure. Orgad, Ron, and Richard and explain the rest and show you how to employ the security features in Oracle Solaris 11 to protect your cloud infrastructure. Part 2 of a three-part article on cloud deployments that use the Oracle Solaris Remote Lab as a case study. About the Photograph That's the fence separating a small group of tourist cabins from a pasture in the small town of Tropic, Utah. Follow Rick on: Personal Blog | Personal Twitter | Oracle Forums   Follow OTN Garage on: Web | Facebook | Twitter | YouTube

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• Fun with Python

  - by dotneteer

  I am taking a class on Coursera recently. My formal education is in physics. Although I have been working as a developer for over 18 years and have learnt a lot of programming on the job, I still would like to gain some systematic knowledge in computer science. Coursera courses taught by Standard professors provided me a wonderful chance. The three languages recommended for assignments are Java, C and Python. I am fluent in Java and have done some projects using C++/MFC/ATL in the past, but I would like to try something different this time. I first started with pure C. Soon I discover that I have to write a lot of code outside the question that I try to solve because the very limited C standard library. For example, to read a list of values from a file, I have to read characters by characters until I hit a delimiter. If I need a list that can grow, I have to create a data structure myself, something that I have taking for granted in .Net or Java. Out of frustration, I switched to Python. I was pleasantly surprised to find that Python is very easy to learn. The tutorial on the official Python site has the exactly the right pace for me, someone with experience in another programming. After a couple of hours on the tutorial and a few more minutes of toying with IDEL, I was in business. I like the “battery supplied” philosophy that gives everything that I need out of box. For someone from C# or Java background, curly braces are replaced by colon(:) and tab spaces. Although I tend to miss colon from time to time, I found that the idea of tab space is actually very nice once I get use to them. I also like to feature of multiple assignment and multiple return parameters. When I need to return a by-product, I just add it to the list of returns. When would use Python? I would use Python if I need to computer anything quick. The language is very easy to use. Python has a good collection of libraries (packages). The REPL of the interpreter allows me test ideas quickly before committing them into script. Lots of computer science work have been ported from Lisp to Python. Some universities are even teaching SICP in Python. When wouldn’t I use Python? I mostly would not use it in a managed environment, such as Ironpython or Jython. Both .Net and Java already have a rich library so one has to make a choice which library to use. If we use the managed runtime library, the code will tie to the particular runtime and thus not portable. If we use the Python library, then we will face the relatively long start-up time. For this reason, I would not recommend to use Ironpython for WP7 development. The only situation that I see merit with managed Python is in a server application where I can preload Python so that the start-up time is not a concern. Using Python as a managed glue language is an over-kill most of the time. A managed Scheme could be a better glue language as it is small enough to start-up very fast.

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• 12.04 GPU lockup

  - by soandos

  I was able to install Ubuntu 12.04 using the alternative version of the image, (64 bit) but when I start the system it tells me the GPU locked up, and instead presents a text only screen. I understand that this site is not for bug reports, but at the same time, I know that there are some versions of the installer than have to be compatible with my graphics card (Nvidia GTS 360M). I assumed that the mere fact that the alternative installer ran was an indication that I could get some sort of graphical interface running after the install. Is there some way of getting some type of graphical interface running on my machine? Even better would be is there a way to get the rest of the system running as normal (i.e. GPU up and running)? If an internet connection is required to download driver support or something similar, directions for how to configure a wireless connection with WPA2-Personal protection from the text-only interface (bash). Any help would be appreciated. Note: I was able to find this which tells me that the card is supported. Note 2: In the install software stage of the install, I was unable to install anything (no internet connection) Update: The exact error message is [8.591394] [drm] 0000:01:00.0: GPU Lockup - switching to software fbcon Update 2: If I try to install with the regular version of Ubuntu, the screen goes staticy. This also happens if I install with Wubi (distasteful I know) and then try to use Ubuntu. Update 3: I've tried xforcevesa, nomodeset and xforcevesa nomodeset as my wubi boot options. Update 4: Thanks to jokerdino, I can now connect to the internet, so internet tools would now be a possibility.

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• Calling COM from Intel Fortran?

  - by user57460

  I'm trying to get COM working from my Fortran application. I do a "COMINITIALIZE" followed by a "COMCreateObjectByProgID". Both of these appear to be successful and return a status of zero. However, when I try to use the COM object, I get "Unhandled exception at 0x00000000 in FortranProg01.exe: 0xC0000005: Access violation." I realize that this error can mean almost anything, but has anyone got some suggestions of common problems with COM that produce this problem? Here are some more details. My program code: program FortranProg01 use myolepg implicit none integer*4 comInitStatus integer:: comCreateStatus INTEGER(INT_PTR_KIND()) $OBJECT INTEGER(4) funcResult REAL(8) pkgVersion call COMINITIALIZE(comInitStatus) print *, comInitStatus call COMCreateObjectByProgID('MyOlePg.MyOlePkg', $OBJECT, comCreateStatus) print *, comCreateStatus funcResult = IMyOlePkg_GetPackageVersion($OBJECT, pkgVersion) print *, funcResult call COMUNINITIALIZE() end program FortranProg01 The wizard-generated interface code: INTERFACE !property PackageVersion INTEGER(4) FUNCTION IMyOlePkg_GetPackageVersion($OBJECT, pVal) INTEGER(INT_PTR_KIND()), INTENT(IN) :: $OBJECT ! Object Pointer !DEC$ ATTRIBUTES VALUE :: $OBJECT REAL(8), INTENT(OUT) :: pVal !DEC$ ATTRIBUTES REFERENCE :: pVal !DEC$ ATTRIBUTES STDCALL :: IMyOlePkg_GetPackageVersion END FUNCTION IMyOlePkg_GetPackageVersion END INTERFACE Any help would be much appreciated! Thanks! Brad.

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• Ping Access to a Nested VM !! Plz Help

  - by Shivaramakrishnan

  I have a problem in communication between the host and the nested VM.This is my layout. I have installed KVM on host machine having a single nic interface (public ip) running Ubuntu.On top of this,I have VM running Ubuntu.I have installed KVM in this VM too.I then have a VM inside this running a web server. I am able to ping the host from this web server VM and ssh into it.But from host to VM ,ping is being unsuccessful. The VM (named L1hyp) on host was created using libvirt-manager and has IP of 192.168.122.8. The vswitch interface created at host is in default config (NAT-ed). Its IP is 192.168.122.1. Now this VM is also having a vswitch interface which is in default config (NAT-ed).Its IP is 192.168.100.1. The Web server VM is created on top of this L1hyp VM, is having an IP of 192.168.100.186. The Webserver VM uses 192.168.100.1 as its default gw. The L1hyp uses 192.168.122.1 as its default gw. From Host: ping 192.168.122.8 - SUCCEEDS ping 192.168.122.1 - SUCCEEDS ping 192.168.100.1 - SUCCEEDS ping 192.168.100.186 - FAILS Comes up with Destination Host Unreachable From 192.168.122.1. But there is route to 192.168.100.0/24 subnet from host.Ping to 192.168.100.1 succeeds. From Webserver VM: ping 192.168.100.1 - SUCCEEDS ping 192.168.122.1 - SUCCEEDS SSH from web server VM to host succeeds. Can anyone help me out what needs to be modified to have two way communication between the host and Webserver VM at the earliest? I am pondering over this problem for over a week now.

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• Call for Papers for both Devoxx UK and France now open!

  - by Yolande

  Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} The two conferences are taking place the last week of March 2013 with London on March 26th and 27 and Paris on March 28th and 29th. Oracle fully supports "Devoxx UK" and "Devoxx France" as a European Platinum Partner. Submit proposals and participate in both conferences since they are a two-hour train ride away from one another. The Devoxx conferences are designed “for developers by developers.” The conference committees are looking for speakers who are passionate developers unafraid to share their knowledge of Java, mobile, web and beyond. The sessions are about frameworks, tools and development with in-depth conference sessions, short practical quickies, and bird-of-a-feather discussions. Those different formats allow speakers to choose the best way to present their topics and can be mentioned during the submission process Devoxx has proven its success under Stephan Janssen, organizer of Devoxx in Belgium for the past 11 years. Devoxx has been the biggest Java conference in Europe for many years. To organize those local conferences, Stephan has enrolled the top community leaders in the UK and France. Ben Evans and Martijn Verberg are the leaders of London Java User Group (JUG) and are also known internationally for starting the Adopt-a-JSR program. Antonio Goncalves is the leader of the Paris JUG. He organized last year’s Devoxx France, which was a big success with twice the size first expected. The organizers made sure to add the local character to the conferences. "The community energy has to feel right," said Ben Evans and for that he picked an "old Victoria hall" for the venue. Those leaders are part of very dynamic Java communities in France and in the UK. France has 22 JUGs; the Paris JUG alone has 2,000 members. The UK has over 50,000 developers working in London and its surroundings; a lot of them are Java developers working in the financial industry. The conference fee is kept as low as possible to encourage those developers to attend. Devoxx promises to be crowded and sold out in advance. Make sure to submit your talks to both Devoxx UK and France before January 31st, 2013. 

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• Dell inspiron not finding Vodafone router

  - by Jeggy

  I have a "Dell inspiron 1564" and ubuntu doesn't find my friends router it works great at home, he has a vodafone router jeggy@jeggy-XPS:~$ sudo lshw -C network *-network description: Wireless interface product: BCM4312 802.11b/g LP-PHY vendor: Broadcom Corporation physical id: 0 bus info: pci@0000:04:00.0 logical name: eth1 version: 01 serial: 78:e4:00:2a:d1:eb width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=wl0 driverversion=5.100.82.38 latency=0 multicast=yes wireless=IEEE 802.11bg resources: irq:17 memory:f0200000-f0203fff *-network description: Ethernet interface product: RTL8101E/RTL8102E PCI Express Fast Ethernet controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:05:00.0 logical name: eth0 version: 02 serial: b8:ac:6f:67:32:52 size: 10Mbit/s capacity: 100Mbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix vpd bus_master cap_list rom ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=half firmware=N/A latency=0 link=no multicast=yes port=MII speed=10Mbit/s resources: irq:42 ioport:3000(size=256) memory:f0410000-f0410fff memory:f0400000-f040ffff memory:f0420000-f043ffff *-network description: Ethernet interface physical id: 4 logical name: ham0 serial: 7a:79:05:ff:3e:ec size: 10Mbit/s capabilities: ethernet physical configuration: autonegotiation=off broadcast=yes driver=tun driverversion=1.6 duplex=full firmware=N/A ip=5.255.62.236 link=yes multicast=yes port=twisted pair speed=10Mbit/s

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• How can I get started using TDD to code some simple functionality?

  - by Gabriel

  I basically have the gist of TDD. I'm sold that it's useful and I've got a reasonable command of the MSTEST framework. However, to date I have not been able to graduate to using it as a primary development method. Mostly, I use it as a surrogate for writing console apps as test drivers (my traditional approach). The most useful thing about it for me is the way it absorbs the role of regression testing. I have not yet built anything yet that specifically isolates various testable behaviors, which is another big part of the picture I know. So this question is to ask for pointers on what the first test(s) I might write for the following development task: I want to produce code that encapsulates task execution in the fashion of producer/consumer. I stopped and decided to write this question after I wrote this code (wondering if I could actually use TDD for real this time) Code: interface ITask { Guid TaskId { get; } bool IsComplete { get; } bool IsFailed { get; } bool IsRunning { get; } } interface ITaskContainer { Guid AddTask(ICommand action); } interface ICommand { string CommandName { get; } Dictionary<string, object> Parameters { get; } void Execute(); }

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• Design pattern for an automated mechanical test bench

  - by JJS

  Background I have a test fixture with a number of communication/data acquisition devices on it that is used as an end of line test for a product. Because of all the various sensors used in the bench and the need to run the test procedure in near real-time, I'm having a hard time structuring the program to be more friendly to modify later on. For example, a National Instruments USB data acquisition device is used to control an analog output (load) and monitor an analog input (current), a digital scale with a serial data interface measures position, an air pressure gauge with a different serial data interface, and the product is interfaced through a proprietary DLL that handles its own serial communication. The hard part The "real-time" aspect of the program is my biggest tripping point. For example, I need to time how long the product needs to go from position 0 to position 10,000 to the tenth of a second. While it's traveling, I need to ramp up an output of the NI DAQ when it reaches position 6,000 and ramp it down when it reaches position 8,000. This sort of control looks easy from browsing NI's LabVIEW docs but I'm stuck with C# for now. All external communication is done by polling which makes for lots of annoying loops. I've slapped together a loose Producer Consumer model where the Producer thread loops through reading the sensors and sets the outputs. The Consumer thread executes functions containing timed loops that poll the Producer for current data and execute movement commands as required. The UI thread polls both threads for updating some gauges indicating current test progress. Unsure where to start Is there a more appropriate pattern for this type of application? Are there any good resources for writing control loops in software (non-LabVIEW) that interface with external sensors and whatnot?

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• Interview Questions in OOP

  - by Fero

  Hi all, I faced the below interview questions in OOP under PHP language. Kindly clear my clarifications regarding this. I am very confused. As i am a beginner to OOP i got too confused. Could anyone clarify these things clearly? Difference between Abstract class and interface. Interviewer : Let us consider abstract class contains three abstract methods such as a,b,c and interface contains three methods a,b,c. In this case these do the same functionality. Then why are going for abstract and why are we going for interface. Me : ? static keyword. Interviewer: We call static method without creating object by using scope resolution operator in PHP. As well as we can able to call concrete methods also. Then what is need of static keyword there? Me : .... final keyword. Interviewer: Give me any scenario of using final keyword. Me : For db connection related method Interviewer: Other than that? Me: ... Constructor. Interviewer: What is the use of constructor? Me : There is no need for object to access this. It will call automatically when the class calls. Interviewer: Other than that? Me : .... Thanks in advance...

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• my web cam not working prperly in skype 12.04

  - by elvin

  oller #1 (rev 02) 00:1d.1 USB controller: Intel Corporation 82801EB/ER (ICH5/ICH5R) USB UHCI Controller #2 (rev 02) 00:1d.2 USB controller: Intel Corporation 82801EB/ER (ICH5/ICH5R) USB UHCI Controller #3 (rev 02) 00:1d.3 USB controller: Intel Corporation 82801EB/ER (ICH5/ICH5R) USB UHCI Controller #4 (rev 02) 00:1d.7 USB controller: Intel Corporation 82801EB/ER (ICH5/ICH5R) USB2 EHCI Controller (rev 02) 00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev c2) 00:1f.0 ISA bridge: Intel Corporation 82801EB/ER (ICH5/ICH5R) LPC Interface Bridge (rev 02) 00:1f.1 IDE interface: Intel Corporation 82801EB/ER (ICH5/ICH5R) IDE Controller (rev 02) 00:1f.2 IDE interface: Intel Corporation 82801EB (ICH5) SATA Controller (rev 02) 00:1f.3 SMBus: Intel Corporation 82801EB/ER (ICH5/ICH5R) SMBus Controller (rev 02) 00:1f.5 Multimedia audio controller: Intel Corporation 82801EB/ER (ICH5/ICH5R) AC'97 Audio Controller (rev 02) 01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10) 01:08.0 Ethernet controller: Intel Corporation 82562EZ 10/100 Ethernet Controller (rev 01) This is the configuration of my web cam when i typed lspci in terminal; how do i find out what type of cam it is. the command letters i wrote here may be wrong.never mind i wrote from my memory.my web cam shows green colour shade and no proper colour.pls help me to fix this problem.2nd option- if i buy microsoft web cam will the image will get corrected.i think my web cam is hyundai electronics make.

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• design for supporting entities with images

  - by brainydexter

  I have multiple entities like Hotels, Destination Cities etc which can contain images. The way I have my system setup right now is, I think of all the images belonging to this universal set (a table in the DB contains filePaths to all the images). When I have to add an image to an entity, I see if the entity exists in this universal set of images. If it exists, attach the reference to this image, else create a new image. E.g.: class ImageEntityHibernateDAO { public void addImageToEntity(IContainImage entity, String filePath, String title, String altText) { ImageEntity image = this.getImage(filePath); if (image == null) image = new ImageEntity(filePath, title, altText); getSession().beginTransaction(); entity.getImages().add(image); getSession().getTransaction().commit(); } } My question is: Earlier I had to write this code for each entity (and each entity would have a Set collection). So, instead of re-writing the same code, I created the following interface: public interface IContainImage { Set<ImageEntity> getImages(); } Entities which have image collections also implements IContainImage interface. Now, for any entity that needs to support adding Image functionality, all I have to invoke from the DAO looks something like this: // in DestinationDAO::addImageToDestination { imageDao.addImageToEntity(destination, imageFileName, imageTitle, imageAltText); // in HotelDAO::addImageToHotel { imageDao.addImageToEntity(hotel, imageFileName, imageTitle, imageAltText); It'd be great help if someone can provide me some critique on this design ? Are there any serious flaws that I'm not seeing right away ?

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• whats the name of this pattern?

  - by Wes

  I see this a lot in frameworks. You have a master class which other classes register with. The master class then decides which of the registered classes to delegate the request to. An example based passed in class may be something this. public interface Processor { public boolean canHandle(Object objectToHandle); public void handle(Object objectToHandle); } public class EvenNumberProcessor extends Processor { public boolean canHandle(Object objectToHandle) { if (!isNumeric(objectToHandle)){ return false } return isEven(objectToHandle); } public void handle(objectToHandle) { //Optionally call canHandleAgain to ensure the calling class is fufilling its contract doSomething(); } } public class OddNumberProcessor extends Processor { public boolean canHandle(Object objectToHandle) { if (!isNumeric(objectToHandle)){ return false } return isOdd(objectToHandle); } public void handle(objectToHandle) { //Optionally call canHandleAgain to ensure the calling class is fufilling its contract doSomething(); } } //Can optionally implement processor interface public class processorDelegator { private List processors; public void addProcessor(Processor processor) { processors.add(processor); } public void process(Object objectToProcess) { //Lookup relevant processor either by keeping a list of what they can process //Or query each one to see if it can process the object. chosenProcessor=chooseProcessor(objectToProcess); chosenProcessor.handle(objectToProcess); } } Note there are a few variations I see on this. In one variation the sub classes provide a list of things they can process which the ProcessorDelegator understands. The other variation which is listed above in fake code is where each is queried in turn. This is similar to chain of command but I don't think its the same as chain of command means that the processor needs to pass to other processors. The other variation is where the ProcessorDelegator itself implements the interface which means you can get trees of ProcessorDelegators which specialise further. In the above example you could have a numeric processor delegator which delegates to an even/odd processor and a string processordelegator which delegates to different strings. My question is does this pattern have a name.

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• Can higher-order functions in FP be interpreted as some kind of dependency injection?

  - by Giorgio

  According to this article, in object-oriented programming / design dependency injection involves a dependent consumer, a declaration of a component's dependencies, defined as interface contracts, an injector that creates instances of classes that implement a given dependency interface on request. Let us now consider a higher-order function in a functional programming language, e.g. the Haskell function filter :: (a -> Bool) -> [a] -> [a] from Data.List. This function transforms a list into another list and, in order to perform its job, it uses (consumes) an external predicate function that must be provided by its caller, e.g. the expression filter (\x -> (mod x 2) == 0) [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] selects all even numbers from the input list. But isn't this construction very similar to the pattern illustrated above, where the filter function is the dependent consumer, the signature (a -> Bool) of the function argument is the interface contract, the expression that uses the higher-order is the injector that, in this particular case, injects the implementation (\x -> (mod x 2) == 0) of the contract. More in general, can one relate higher-order functions and their usage pattern in functional programming to the dependency injection pattern in object-oriented languages? Or in the inverse direction, can dependency injection be compared to using some kind of higher-order function?

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