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• How to connect to ESX Server Storage To Upload VM Images

  - by dotnetgeek

  I am trying to figure out how I can connect to an ESX server's storage system so that I can upload VM image files. I am a windows user if that matters (i suspect it does). Thanks in advance

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• Minimize useless tweaking of a numeric app

  - by Potatoswatter

  I'm developing a numeric application (nonlinear optimizer), with a zillion knobs to tweak and rising. It's not my first foray into this domain, but this time there are even more variables in the code and I'm on a tight schedule. Don't want to waste time fiddling. Days or even months can potentially be wasted adjusting variables, recompiling, and reprocessing benchmark datasets. The resulting data is viewed and trouble spots are checked. The overall quality of the solution is reported by the program but the meaning of the report could change over time. (Numeric units for the report are one thing I'm trying to nail down.) One main problem is organizing result files to identify each with specific code changes. Note taking can be a pain, is there software to help with this? Are there agreed best practices to making this kind of development cycle reliably move forward? The solver package converges to its optimal solution with mechanical determination, but I'm all too familiar with the way an excess of design decisions can mire development.

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• Prioritize compiler functionality/tasks, when designing a new language

  - by Mahdi

  Well, the question should be so hard to ask and I expect couple of down votes, however, I'm really interested to have your ideas and recommendations. :) I've already made a very simple compiler, with a few and limited functionality. Now I'm getting more on it to make it more like a real-world compiler. I definitely need to start over 'cause I've much more experience and ideas in this area rather a few years ago. So, I want to know, right now, from the very first step again, which tasks/features for the new compiler should implement first and which tasks has lower priority rather than others? For example, I'd say, first I'd go to decide about the object-oriented structure for the new language, but you might say, hey, just go for a compiler that could define a variable, when you finished that, then start thinking about OOP designs ... I prefer to hear the pros and cons for your suggestions also. Actually I like to start from Bottom to Top, where I could add simplest tasks first, and later adding more complex ones, but I'm totally open for any new ideas, and really appreciate that. Also please consider that I'm thinking about the design concepts. Actually I expect answers like: Priority from Highest to Lowest: variables, because .... functions, because .... loops, because .... ... Not: define a syntax for your new language, and start parsing your source code ...

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• Struggling with the Single Responsibility Principle

  - by AngryBird

  Consider this example: I have a website. It allows users to make posts (can be anything) and add tags that describe the post. In the code, I have two classes that represent the post and tags. Lets call these classes Post and Tag. Post takes care of creating posts, deleting posts, updating posts, etc. Tag takes care of creating tags, deleting tags, updating tags, etc. There is one operation that is missing. The linking of tags to posts. I am struggling with who should do this operation. It could fit equally well in either class. On one hand, the Post class could have a function that takes a Tag as a parameter, and then stores it in a list of tags. On the other hand, the Tag class could have a function that takes a Post as a parameter and links the Tag to the Post. The above is just an example of my problem. I am actually running into this with multiple classes that are all similar. It could fit equally well in both. Short of actually putting the functionality in both classes, what conventions or design styles exist to help me solve this problem. I am assuming there has to be something short of just picking one? Maybe putting it in both classes is the correct answer?

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• From a DDD perspective is a report generating service a domain service or an infrastructure service?

  - by Songo

  Let assume we have the following service whose responsibility is to generate Excel reports: class ExcelReportService{ public String generateReport(String fileFormatFilePath, ResultSet data){ ReportFormat reportFormat = new ReportFormat(fileFormatFilePath); ExcelDataFormatterService excelDataFormatterService = new ExcelDataFormatterService(); FormattedData formattedData = excelDataFormatterService.format(data); ExcelFileService excelFileService = new ExcelFileService(); String reportPath= excelFileService.generateReport(reportFormat,formattedData); return reportPath; } } This is pseudo code for the service I want to design where: fileFormatFilePath: path to a configuration file where I'll keep the format of my excel file (headers, column widths, number of columns,..etc) data: the actual records returned from the database. This data can't be used directly coz I might need to make further calculations to the data before inserting them to the excel file. ReportFormat: Value object to hold the report format, has methods like getHeaders(), getColumnWidth(),...etc. ExcelDataFormatterService: a service to hold any logic that need to be applied to the data returned from the database before inserting it to the file. FormattedData: Value object the represents the formatted data to be inserted. ExcelFileService: a wrapper top the 3rd party library that generates the excel file. Now how do you determine whether a service is an infrastructure or domain service? I have the following 3 services here: ExcelReportService, ExcelDataFormatterService and ExcelFileService?

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• Implementing a ILogger interface to log data

  - by Jon

  I have a need to write data to file in one of my classes. Obviously I will pass an interface into my class to decouple it. I was thinking this interface will be used for testing and also in other projects. This is my interface: //This could be used by filesystem, webservice public interface ILogger { List<string> PreviousLogRecords {get;set;} void Log(string Data); } public interface IFileLogger : ILogger { string FilePath; bool ValidFileName; } public class MyClassUnderTest { public MyClassUnderTest(IFileLogger logger) {....} } [Test] public void TestLogger() { var mock = new Mock<IFileLogger>(); mock.Setup(x => x.Log(Is.Any<string>).AddsDataToList()); //Is this possible?? var myClass = new MyClassUnderTest(mock.Object); myClass.DoSomethingThatWillSplitThisAndLog3Times("1,2,3"); Assert.AreEqual(3,mock.PreviousLogRecords.Count); } This won't work I don't believe as nothing is storing the items so is this possible using Moq and also what do you think of the design of the interface?

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• Handling Types for Real and Complex Matrices in a BLAS Wrapper

  - by mga

  I come from a C background and I'm now learning OOP with C++. As an exercise (so please don't just say "this already exists"), I want to implement a wrapper for BLAS that will let the user write matrix algebra in an intuitive way (e.g. similar to MATLAB) e.g.: A = B*C*D.Inverse() + E.Transpose(); My problem is how to go about dealing with real (R) and complex (C) matrices, because of C++'s "curse" of letting you do the same thing in N different ways. I do have a clear idea of what it should look like to the user: s/he should be able to define the two separately, but operations would return a type depending on the types of the operands (R*R = R, C*C = C, R*C = C*R = C). Additionally R can be cast into C and vice versa (just by setting the imaginary parts to 0). I have considered the following options: As a real number is a special case of a complex number, inherit CMatrix from RMatrix. I quickly dismissed this as the two would have to return different types for the same getter function. Inherit RMatrix and CMatrix from Matrix. However, I can't really think of any common code that would go into Matrix (because of the different return types). Templates. Declare Matrix<T> and declare the getter function as T Get(int i, int j), and operator functions as Matrix *(Matrix RHS). Then specialize Matrix<double> and Matrix<complex>, and overload the functions. Then I couldn't really see what I would gain with templates, so why not just define RMatrix and CMatrix separately from each other, and then overload functions as necessary? Although this last option makes sense to me, there's an annoying voice inside my head saying this is not elegant, because the two are clearly related. Perhaps I'm missing an appropriate design pattern? So I guess what I'm looking for is either absolution for doing this, or advice on how to do better.

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• Parameterized Django models

  - by mgibsonbr

  In principle, a single Django application can be reused in two or more projects, providing functionality relevent to both. That implies that the same database structure (tables and relations) will be re-created identically in different databases, and most times this is not a problem (assuming the projects/databases are unrelated - for instance when someone downloads a complete app to use in their own projects). Sometimes, however, the models must be "tweaked" a little to better fit the problem needs. This can be accomplished by forking the app, but I wondered if there wouldn't be a better option in cases where the app designer can anticipate the most common customizations. For instance, if I have a model that could relate to another as one-to-one or one-to-many, I could specify the unique property as a parameter, that can be specified in the project's settings: class This(models.Model): other = models.ForeignKey(Other, unique=settings.OTHER_TO_THIS) Or if a model can relate to many others, I could create an intermediate table for each of them (thus enforcing referential integrity) instead of using generic fks: for related in settings.MODELS_RELATED_TO_OTHER: model_name = '%s_Other' % related globals()[model_name] = type(model_name, (models.Model,) { me:models.ForeignKey(find_model_class(related)), other:models.ForeignKey(Other), # Some other properties all intersection tables must have }) Etc. Let me stress out that I'm not proposing to change the models at runtime nor anything like that; once the parameters were defined and syncdb called for the first time, those parameters are not to be changed again (unless you're doing a schema migration). Is this a good design? Are there better ways to accomplish the same thing, or maybe drawbacks I coulnd't anticipate? This technique is meant to be used sparingly (only on apps meant to be reused in wildly different contexts, and only when a specific need of customization can be detected while the app model is being designed).

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• Best practice to collect information from child objects

  - by Markus

  I'm regularly seeing the following pattern: public abstract class BaseItem { BaseItem[] children; // ... public void DoSomethingWithStuff() { StuffCollection collection = new StuffCollection(); foreach(child c : children) c.AddRequiredStuff(collection); // do something with the collection ... } public abstract void AddRequiredStuff(StuffCollection collection); } public class ConcreteItem : BaseItem { // ... public override void AddRequiredStuff(StuffCollection collection) { Stuff stuff; // ... collection.Add(stuff); } } Where I would use something like this, for better information hiding: public abstract class BaseItem { BaseItem[] children; // ... public void DoSomethingWithStuff() { StuffCollection collection = new StuffCollection(); foreach(child c : children) collection.AddRange(c.RequiredStuff()); // do something with the collection ... } public abstract StuffCollection RequiredStuff(); } public class ConcreteItem : BaseItem { // ... public override StuffCollection RequiredStuff() { StuffCollection stuffCollection; Stuff stuff; // ... stuffCollection.Add(stuff); return stuffCollection; } } What are pros and cons of each solution? For me, giving the implementation access to parent's information is some how disconcerting. On the other hand, initializing a new list, just to collect the items is a useless overhead ... What is the better design? How would it change, if DoSomethingWithStuff wouldn't be part of BaseItem but a third class? PS: there might be missing semicolons, or typos; sorry for that! The above code is not meant to be executed, but just for illustration.

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• Classes as a compilation unit

  - by Yannbane

  If "compilation unit" is unclear, please refer to this. However, what I mean by it will be clear from the context. Edit: my language allows for multiple inheritance, unlike Java. I've started designing+developing my own programming language for educational, recreational, and potentially useful purposes. At first, I've decided to base it off Java. This implied that I would have all the code be written inside classes, and that code compiles to classes, which are loaded by the VM. However, I've excluded features such as interfaces and abstract classes, because I found no need for them. They seemed to be enforcing a paradigm, and I'd like my language not to do that. I wanted to keep the classes as the compilation unit though, because it seemed convenient to implement, familiar, and I just liked the idea. Then I noticed that I'm basically left with a glorified module system, where classes could be used either as "namespaces", providing constants and functions using the static directive, or as templates for objects that need to be instantiated ("actual" purpose of classes in other languages). Now I'm left wondering: what are the benefits of having classes as compilation units? (Also, any general commentary on my design would be much appreciated.)

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• DB Object passing between classes singleton, static or other?

  - by Stephen

  So I'm designing a reporting system at work it's my first project written OOP and I'm stuck on the design choice for the DB class. Obviously I only want to create one instance of the DB class per-session/user and then pass it to each of the classes that need it. What I don't know it what's best practice for implementing this. Currently I have code like the following:- class db { private $user = 'USER'; private $pass = 'PASS'; private $tables = array( 'user','report', 'etc...'); function __construct(){ //SET UP CONNECTION AND TABLES } }; class report{ function __construct ($params = array(), $db, $user) { //Error checking/handling trimed //$db is the database object we created $this->db = $db; //$this->user is the user object for the logged in user $this->user = $user; $this->reportCreate(); } public function setPermission($permissionId = 1) { //Note the $this->db is this the best practise solution? $this->db->permission->find($permissionId) //Note the $this->user is this the best practise solution? $this->user->checkPermission(1) $data=array(); $this->db->reportpermission->insert($data) } };//end report I've been reading about using static classes and have just come across Singletons (though these appear to be passé already?) so what's current best practice for doing this?

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• Tips for Making this Code Testable [migrated]

  - by Jesse Bunch

  So I'm writing an abstraction layer that wraps a telephony RESTful service for sending text messages and making phone calls. I should build this in such a way that the low-level provider, in this case Twilio, can be easily swapped without having to re-code the higher level interactions. I'm using a package that is pre-built for Twilio and so I'm thinking that I need to create a wrapper interface to standardize the interaction between the Twilio service package and my application. Let us pretend that I cannot modify this pre-built package. Here is what I have so far (in PHP): <?php namespace Telephony; class Provider_Twilio implements Provider_Interface { public function send_sms(Provider_Request_SMS $request) { if (!$request->is_valid()) throw new Provider_Exception_InvalidRequest(); $sms = \Twilio\Twilio::request('SmsMessage'); $response = $sms->create(array( 'To' => $request->to, 'From' => $request->from, 'Body' => $request->body )); if ($this->_did_request_fail($response)) { throw new Provider_Exception_RequestFailed($response->message); } $response = new Provider_Response_SMS(TRUE); return $response; } private function _did_request_fail($api_response) { return isset($api_response->status); } } So the idea is that I can write another file like this for any other telephony service provided that it implements Provider_Interface making them swappable. Here are my questions: First off, do you think this is a good design? How could it be improved? Second, I'm having a hard time testing this because I need to mock out the Twilio package so that I'm not actually depending on Twilio's API for my tests to pass or fail. Do you see any strategy for mocking this out? Thanks in advance for any advice!

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• Creating basic, redundant gigE or IB storage network for Xen?

  - by StaringSkyward

  With only a modest budget, I want to move my 4 xen servers over to network storage -either NFS or iSCSI which will be determined based on how well it performs when we test it (we need good throughput and it must continue to work through link and switch failure tests). We may add another couple of xen servers at some point when this is done. I don't know much about the design and operation of storage networks, so would really appreciate some hints from those with experience. The budget is around $3,800 excluding the storage appliance. I am currently thinking these are my options to remain on budget: 1) Go for used infiniband hardware and aim for 10gb performance. 2) Stick with gig ethernet and buy some new switches (cisco or procurve) to create a storage-only ethernet LAN. Upgrade to 10gigE later but try to use hardware capable of it where possible to reduce upgrade costs. I have seen used, warrantied infiniband switches at reasonable prices (presumably because big companies are converging on 10gbit ethernet?) and the promise of cheap 10gb is attractive. I know nothing about IB, so here come the questions: Can I buy 2 x switches and have multiple HBAs in my xen and storage nodes to get redundancy and increased performance without complexity or expensive management software costs? If so, can you point me to some examples? Do NFS and iSCSI work just the same regardless? Is IB a sensible choice or could/should I use ethernet or FC on the same budget - I'm keen not to get boxed into a corner for future upgrades, however. For the storage I am likely to build a storage server using nexentastor with the intention that I can later add more disks, SSDs and add another server to provide a failover option at the storage level. An HP LeftHand starter SAN is also under consideration, too. Thanks in advance.

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• Oracle Solaris: Zones on Shared Storage

  - by Jeff Victor

  Oracle Solaris 11.1 has several new features. At oracle.com you can find a detailed list. One of the significant new features, and the most significant new feature releated to Oracle Solaris Zones, is casually called "Zones on Shared Storage" or simply ZOSS (rhymes with "moss"). ZOSS offers much more flexibility because you can store Solaris Zones on shared storage (surprise!) so that you can perform quick and easy migration of a zone from one system to another. This blog entry describes and demonstrates the use of ZOSS. ZOSS provides complete support for a Solaris Zone that is stored on "shared storage." In this case, "shared storage" refers to fiber channel (FC) or iSCSI devices, although there is one lone exception that I will demonstrate soon. The primary intent is to enable you to store a zone on FC or iSCSI storage so that it can be migrated from one host computer to another much more easily and safely than in the past. With this blog entry, I wanted to make it easy for you to try this yourself. I couldn't assume that you have a SAN available - which is a good thing, because neither do I! What could I use, instead? [There he goes, foreshadowing again... -Ed.] Developing this entry reinforced the lesson that the solution to every lab problem is VirtualBox. Oracle VM VirtualBox (its formal name) helps here in a couple of important ways. It offers the ability to easily install multiple copies of Solaris as guests on top of any popular system (Microsoft Windows, MacOS, Solaris, Oracle Linux (and other Linuxes) etc.). It also offers the ability to create a separate virtual disk drive (VDI) that appears as a local hard disk to a guest. This virtual disk can be moved very easily from one guest to another. In other words, you can follow the steps below on a laptop or larger x86 system. Please note that the ability to use ZOSS to store a zone on a local disk is very useful for a lab environment, but not so useful for production. I do not suggest regularly moving disk drives among computers. In the method I describe below, that virtual hard disk will contain the zone that will be migrated among the (virtual) hosts. In production, you would use FC or iSCSI LUNs instead. The zonecfg(1M) man page details the syntax for each of the three types of devices. Why Migrate? Why is the migration of virtual servers important? Some of the most common reasons are: Moving a workload to a different computer so that the original computer can be turned off for extensive maintenance. Moving a workload to a larger system because the workload has outgrown its original system. If the workload runs in an environment (such as a Solaris Zone) that is stored on shared storage, you can restore the service of the workload on an alternate computer if the original computer has failed and will not reboot. You can simplify lifecycle management of a workload by developing it on a laptop, migrating it to a test platform when it's ready, and finally moving it to a production system. Concepts For ZOSS, the important new concept is named "rootzpool". You can read about it in the zonecfg(1M) man page, but here's the short version: it's the backing store (hard disk(s), or LUN(s)) that will be used to make a ZFS zpool - the zpool that will hold the zone. This zpool: contains the zone's Solaris content, i.e. the root file system does not contain any content not related to the zone can only be mounted by one Solaris instance at a time Method Overview Here is a brief list of the steps to create a zone on shared storage and migrate it. The next section shows the commands and output. You will need a host system with an x86 CPU (hopefully at least a couple of CPU cores), at least 2GB of RAM, and at least 25GB of free disk space. (The steps below will not actually use 25GB of disk space, but I don't want to lead you down a path that ends in a big sign that says "Your HDD is full. Good luck!") Configure the zone on both systems, specifying the rootzpool that both will use. The best way is to configure it on one system and then copy the output of "zonecfg export" to the other system to be used as input to zonecfg. This method reduces the chances of pilot error. (It is not necessary to configure the zone on both systems before creating it. You can configure this zone in multiple places, whenever you want, and migrate it to one of those places at any time - as long as those systems all have access to the shared storage.) Install the zone on one system, onto shared storage. Boot the zone. Provide system configuration information to the zone. (In the Real World(tm) you will usually automate this step.) Shutdown the zone. Detach the zone from the original system. Attach the zone to its new "home" system. Boot the zone. The zone can be used normally, and even migrated back, or to a different system. Details The rest of this shows the commands and output. The two hostnames are "sysA" and "sysB". Note that each Solaris guest might use a different device name for the VDI that they share. I used the device names shown below, but you must discover the device name(s) after booting each guest. In a production environment you would also discover the device name first and then configure the zone with that name. Fortunately, you can use the command "zpool import" or "format" to discover the device on the "new" host for the zone. The first steps create the VirtualBox guests and the shared disk drive. I describe the steps here without demonstrating them. Download VirtualBox and install it using a method normal for your host OS. You can read the complete instructions. Create two VirtualBox guests, each to run Solaris 11.1. Each will use its own VDI as its root disk. Install Solaris 11.1 in each guest.Install Solaris 11.1 in each guest. To install a Solaris 11.1 guest, you can either download a pre-built VirtualBox guest, and import it, or install Solaris 11.1 from the "text install" media. If you use the latter method, after booting you will not see a windowing system. To install the GUI and other important things, login and run "pkg install solaris-desktop" and take a break while it installs those important things. Life is usually easier if you install the VirtualBox Guest Additions because then you can copy and paste between the host and guests, etc. You can find the guest additions in the folder matching the version of VirtualBox you are using. You can also read the instructions for installing the guest additions. To create the zone's shared VDI in VirtualBox, you can open the storage configuration for one of the two guests, select the SATA controller, and click on the "Add Hard Disk" icon nearby. Choose "Create New Disk" and specify an appropriate path name for the file that will contain the VDI. The shared VDI must be at least 1.5 GB. Note that the guest must be stopped to do this. Add that VDI to the other guest - using its Storage configuration - so that each can access it while running. The steps start out the same, except that you choose "Choose Existing Disk" instead of "Create New Disk." Because the disk is configured on both of them, VirtualBox prevents you from running both guests at the same time. Identify device names of that VDI, in each of the guests. Solaris chooses the name based on existing devices. The names may be the same, or may be different from each other. This step is shown below as "Step 1." Assumptions In the example shown below, I make these assumptions. The guest that will own the zone at the beginning is named sysA. The guest that will own the zone after the first migration is named sysB. On sysA, the shared disk is named /dev/dsk/c7t2d0 On sysB, the shared disk is named /dev/dsk/c7t3d0 (Finally!) The Steps Step 1) Determine the name of the disk that will move back and forth between the systems. root@sysA:~# format Searching for disks...done AVAILABLE DISK SELECTIONS: 0. c7t0d0 /pci@0,0/pci8086,2829@d/disk@0,0 1. c7t2d0 /pci@0,0/pci8086,2829@d/disk@2,0 Specify disk (enter its number): ^D Step 2) The first thing to do is partition and label the disk. The magic needed to write an EFI label is not overly complicated. root@sysA:~# format -e c7t2d0 selecting c7t2d0 [disk formatted] FORMAT MENU: ... format fdisk No fdisk table exists. The default partition for the disk is: a 100% "SOLARIS System" partition Type "y" to accept the default partition, otherwise type "n" to edit the partition table. n SELECT ONE OF THE FOLLOWING: ... Enter Selection: 1 ... G=EFI_SYS 0=Exit? f SELECT ONE... ... 6 format label ... Specify Label type[1]: 1 Ready to label disk, continue? y format quit root@sysA:~# ls /dev/dsk/c7t2d0 /dev/dsk/c7t2d0 Step 3) Configure zone1 on sysA. root@sysA:~# zonecfg -z zone1 Use 'create' to begin configuring a new zone. zonecfg:zone1 create create: Using system default template 'SYSdefault' zonecfg:zone1 set zonename=zone1 zonecfg:zone1 set zonepath=/zones/zone1 zonecfg:zone1 add rootzpool zonecfg:zone1:rootzpool add storage dev:dsk/c7t2d0 zonecfg:zone1:rootzpool end zonecfg:zone1 exit root@sysA:~# oot@sysA:~# zonecfg -z zone1 info zonename: zone1 zonepath: /zones/zone1 brand: solaris autoboot: false bootargs: file-mac-profile: pool: limitpriv: scheduling-class: ip-type: exclusive hostid: fs-allowed: anet: ... rootzpool: storage: dev:dsk/c7t2d0 Step 4) Install the zone. This step takes the most time, but you can wander off for a snack or a few laps around the gym - or both! (Just not at the same time...) root@sysA:~# zoneadm -z zone1 install Created zone zpool: zone1_rpool Progress being logged to /var/log/zones/zoneadm.20121022T163634Z.zone1.install Image: Preparing at /zones/zone1/root. AI Manifest: /tmp/manifest.xml.RXaycg SC Profile: /usr/share/auto_install/sc_profiles/enable_sci.xml Zonename: zone1 Installation: Starting ... Creating IPS image Startup linked: 1/1 done Installing packages from: solaris origin: http://pkg.us.oracle.com/support/ DOWNLOAD PKGS FILES XFER (MB) SPEED Completed 183/183 33556/33556 222.2/222.2 2.8M/s PHASE ITEMS Installing new actions 46825/46825 Updating package state database Done Updating image state Done Creating fast lookup database Done Installation: Succeeded Note: Man pages can be obtained by installing pkg:/system/manual done. Done: Installation completed in 1696.847 seconds. Next Steps: Boot the zone, then log into the zone console (zlogin -C) to complete the configuration process. Log saved in non-global zone as /zones/zone1/root/var/log/zones/zoneadm.20121022T163634Z.zone1.install Step 5) Boot the Zone. root@sysA:~# zoneadm -z zone1 boot Step 6) Login to zone's console to complete the specification of system information. root@sysA:~# zlogin -C zone1 Answer the usual questions and wait for a login prompt. Then you can end the console session with the usual "~." incantation. Step 7) Shutdown the zone so it can be "moved." root@sysA:~# zoneadm -z zone1 shutdown Step 8) Detach the zone so that the original global zone can't use it. root@sysA:~# zoneadm list -cv ID NAME STATUS PATH BRAND IP 0 global running / solaris shared - zone1 installed /zones/zone1 solaris excl root@sysA:~# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT rpool 17.6G 11.2G 6.47G 63% 1.00x ONLINE - zone1_rpool 1.98G 484M 1.51G 23% 1.00x ONLINE - root@sysA:~# zoneadm -z zone1 detach Exported zone zpool: zone1_rpool Step 9) Review the result and shutdown sysA so that sysB can use the shared disk. root@sysA:~# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT rpool 17.6G 11.2G 6.47G 63% 1.00x ONLINE - root@sysA:~# zoneadm list -cv ID NAME STATUS PATH BRAND IP 0 global running / solaris shared - zone1 configured /zones/zone1 solaris excl root@sysA:~# init 0 Step 10) Now boot sysB and configure a zone with the parameters shown above in Step 1. (Again, the safest method is to use "zonecfg ... export" on sysA as described in section "Method Overview" above.) The one difference is the name of the rootzpool storage device, which was shown in the list of assumptions, and which you must determine by booting sysB and using the "format" or "zpool import" command. When that is done, you should see the output shown next. (I used the same zonename - "zone1" - in this example, but you can choose any valid zonename you want.) root@sysB:~# zoneadm list -cv ID NAME STATUS PATH BRAND IP 0 global running / solaris shared - zone1 configured /zones/zone1 solaris excl root@sysB:~# zonecfg -z zone1 info zonename: zone1 zonepath: /zones/zone1 brand: solaris autoboot: false bootargs: file-mac-profile: pool: limitpriv: scheduling-class: ip-type: exclusive hostid: fs-allowed: anet: linkname: net0 ... rootzpool: storage: dev:dsk/c7t3d0 Step 11) Attaching the zone automatically imports the zpool. root@sysB:~# zoneadm -z zone1 attach Imported zone zpool: zone1_rpool Progress being logged to /var/log/zones/zoneadm.20121022T184034Z.zone1.attach Installing: Using existing zone boot environment Zone BE root dataset: zone1_rpool/rpool/ROOT/solaris Cache: Using /var/pkg/publisher. Updating non-global zone: Linking to image /. Processing linked: 1/1 done Updating non-global zone: Auditing packages. No updates necessary for this image. Updating non-global zone: Zone updated. Result: Attach Succeeded. Log saved in non-global zone as /zones/zone1/root/var/log/zones/zoneadm.20121022T184034Z.zone1.attach root@sysB:~# zoneadm -z zone1 boot root@sysB:~# zlogin zone1 [Connected to zone 'zone1' pts/2] Oracle Corporation SunOS 5.11 11.1 September 2012 Step 12) Now let's migrate the zone back to sysA. Create a file in zone1 so we can verify it exists after we migrate the zone back, then begin migrating it back. root@zone1:~# ls /opt root@zone1:~# touch /opt/fileA root@zone1:~# ls -l /opt/fileA -rw-r--r-- 1 root root 0 Oct 22 14:47 /opt/fileA root@zone1:~# exit logout [Connection to zone 'zone1' pts/2 closed] root@sysB:~# zoneadm -z zone1 shutdown root@sysB:~# zoneadm -z zone1 detach Exported zone zpool: zone1_rpool root@sysB:~# init 0 Step 13) Back on sysA, check the status. Oracle Corporation SunOS 5.11 11.1 September 2012 root@sysA:~# zoneadm list -cv ID NAME STATUS PATH BRAND IP 0 global running / solaris shared - zone1 configured /zones/zone1 solaris excl root@sysA:~# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT rpool 17.6G 11.2G 6.47G 63% 1.00x ONLINE - Step 14) Re-attach the zone back to sysA. root@sysA:~# zoneadm -z zone1 attach Imported zone zpool: zone1_rpool Progress being logged to /var/log/zones/zoneadm.20121022T190441Z.zone1.attach Installing: Using existing zone boot environment Zone BE root dataset: zone1_rpool/rpool/ROOT/solaris Cache: Using /var/pkg/publisher. Updating non-global zone: Linking to image /. Processing linked: 1/1 done Updating non-global zone: Auditing packages. No updates necessary for this image. Updating non-global zone: Zone updated. Result: Attach Succeeded. Log saved in non-global zone as /zones/zone1/root/var/log/zones/zoneadm.20121022T190441Z.zone1.attach root@sysA:~# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT rpool 17.6G 11.2G 6.47G 63% 1.00x ONLINE - zone1_rpool 1.98G 491M 1.51G 24% 1.00x ONLINE - root@sysA:~# zoneadm -z zone1 boot root@sysA:~# zlogin zone1 [Connected to zone 'zone1' pts/2] Oracle Corporation SunOS 5.11 11.1 September 2012 root@zone1:~# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT rpool 1.98G 538M 1.46G 26% 1.00x ONLINE - Step 15) Check for the file created on sysB, earlier. root@zone1:~# ls -l /opt total 1 -rw-r--r-- 1 root root 0 Oct 22 14:47 fileA Next Steps Here is a brief list of some of the fun things you can try next. Add space to the zone by adding a second storage device to the rootzpool. Make sure that you add it to the configurations of both zones! Create a new zone, specifying two disks in the rootzpool when you first configure the zone. When you install that zone, or clone it from another zone, zoneadm uses those two disks to create a mirrored pool. (Three disks will result in a three-way mirror, etc.) Conclusion Hopefully you have seen the ease with which you can now move Solaris Zones from one system to another.

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• Domain Models (PHP)

  - by Calum Bulmer

  I have been programming in PHP for several years and have, in the past, adopted methods of my own to handle data within my applications. I have built my own MVC, in the past, and have a reasonable understanding of OOP within php but I know my implementation needs some serious work. In the past I have used an is-a relationship between a model and a database table. I now know after doing some research that this is not really the best way forward. As far as I understand it I should create models that don't really care about the underlying database (or whatever storage mechanism is to be used) but only care about their actions and their data. From this I have established that I can create models of lets say for example a Person an this person object could have some Children (human children) that are also Person objects held in an array (with addPerson and removePerson methods, accepting a Person object). I could then create a PersonMapper that I could use to get a Person with a specific 'id', or to save a Person. This could then lookup the relationship data in a lookup table and create the associated child objects for the Person that has been requested (if there are any) and likewise save the data in the lookup table on the save command. This is now pushing the limits to my knowledge..... What if I wanted to model a building with different levels and different rooms within those levels? What if I wanted to place some items in those rooms? Would I create a class for building, level, room and item with the following structure. building can have 1 or many level objects held in an array level can have 1 or many room objects held in an array room can have 1 or many item objects held in an array and mappers for each class with higher level mappers using the child mappers to populate the arrays (either on request of the top level object or lazy load on request) This seems to tightly couple the different objects albeit in one direction (ie. a floor does not need to be in a building but a building can have levels) Is this the correct way to go about things? Within the view I am wanting to show a building with an option to select a level and then show the level with an option to select a room etc.. but I may also want to show a tree like structure of items in the building and what level and room they are in. I hope this makes sense. I am just struggling with the concept of nesting objects within each other when the general concept of oop seems to be to separate things. If someone can help it would be really useful. Many thanks

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• 7 Web Design Tutorials from PSD to HTML/CSS

  - by Sushaantu

  Some time back when I was looking for some tutorials to create a website from scratch i.e. the process from designing the PSD to slice it and CSS/XHTML it, then not many quality results appeared. But that was like almost an year back and a lot of water has flown down the river Thanes since then. In this list I will give you links to some wonderful tutorials teaching you in a step by step way to design a website. These tutorials are ideal for someone who is learning web designing and has grasp of basic CSS, XHTML and little designing on Photoshop. How to Design and Code Web 2.0 Style Web Design Design a website from PSD to HTML Designing and Coding a Grunge Web Design from Scratch Creating a CSS layout from scratch Build a Sleek Portfolio Site from Scratch Designing and Coding a web design from scratch Design and Code a Dark and Sleek Web Design

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• Getting started with modern software architecture and design using a book

  - by bitbonk

  I am a rather oldschool developer with some basic knowledge of software design principles and a good background on classic (gof) design patterns. While I continue my life as such I see lots of strange buzzwords emerge: Aspectoriented Design, Componentoriented Design, Domain Driven Design, Domain Specific Languages, Serviceoriented (SOA) Design, Test Driven Design, Extreme Programming, Agile Development, Continuous Integration, Dependency Injection, Software Factories ... Is there good book around that I can take with me on a roadtrip while it is taking me on a trip through all (most) of the above, delivering an 10,000 foot view on modern software archiceture and desing principles and approaches.

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• Composite-like pattern and SRP violation

  - by jimmy_keen

  Recently I've noticed myself implementing pattern similar to the one described below. Starting with interface: public interface IUserProvider { User GetUser(UserData data); } GetUser method's pure job is to somehow return user (that would be an operation speaking in composite terms). There might be many implementations of IUserProvider, which all do the same thing - return user basing on input data. It doesn't really matter, as they are only leaves in composite terms and that's fairly simple. Now, my leaves are used by one own them all composite class, which at the moment follows this implementation: public interface IUserProviderComposite : IUserProvider { void RegisterProvider(Predicate<UserData> predicate, IUserProvider provider); } public class UserProviderComposite : IUserProviderComposite { public User GetUser(SomeUserData data) ... public void RegisterProvider(Predicate<UserData> predicate, IUserProvider provider) ... } Idea behind UserProviderComposite is simple. You register providers, and this class acts as a reusable entry-point. When calling GetUser, it will use whatever registered provider matches predicate for requested user data (if that helps, it stores key-value map of predicates and providers internally). Now, what confuses me is whether RegisterProvider method (brings to mind composite's add operation) should be a part of that class. It kind of expands its responsibilities from providing user to also managing providers collection. As far as my understanding goes, this violates Single Responsibility Principle... or am I wrong here? I thought about extracting register part into separate entity and inject it to the composite. As long as it looks decent on paper (in terms of SRP), it feels bit awkward because: I would be essentially injecting Dictionary (or other key-value map) ...or silly wrapper around it, doing nothing more than adding entires This won't be following composite anymore (as add won't be part of composite) What exactly is the presented pattern called? Composite felt natural to compare it with, but I realize it's not exactly the one however nothing else rings any bells. Which approach would you take - stick with SRP or stick with "composite"/pattern? Or is the design here flawed and given the problem this can be done in a better way?

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• HTML5 Web Storage Cleared when Browser Clear Cache?

  - by jiewmeng

  i wonder if HTML5 Web Storage will be cleared when browser clears its cache? if it did, many ppl like me may lose data if i accidentally clear cache? or like in this comment ... Since HTML5 local storage is kept separate from js cookies (like Silverlight, Gears, Flash), it opens up a world of 3rd party privacy issues for HTML5 as these objects will likely NOT get deleted with a clear cache or delete temporary data ... where web storage is not cleared, but leads to privacy issues?

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• What's a good video upload storage solution?

  - by Nikko

  What's a good video upload storage solution? I'm trying to find a way to offload bandwidth to another storage solution (something like S3), but at the same time, also trying to find a solution which is geared for video storage. Are there any solutions out there for this? Or should I just use S3? Thanks!

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• A sample Memento pattern: Is it correct?

  - by TheSilverBullet

  Following this query on memento pattern, I have tried to put my understanding to test. Memento pattern stands for three things: Saving state of the "memento" object for its successful retrieval Saving carefully each valid "state" of the memento Encapsulating the saved states from the change inducer so that each state remains unaltered Have I achieved these three with my design? Problem This is a zero player game where the program is initialized with a particular set up of chess pawns - the knight and queen. Then program then needs to keep adding set of pawns or knights and queens so that each pawn is "safe" for the next one move of every other pawn. The condition is that either both pawns should be placed, or none of them should be placed. The chessboard with the most number of non conflicting knights and queens should be returned. Implementation I have 4 classes for this: protected ChessBoard (the Memento) private int [][] ChessBoard; public void ChessBoard(); protected void SetChessBoard(); protected void GetChessBoard(int); public Pawn This is not related to memento. It holds info about the pawns public enum PawnType: int { Empty = 0, Queen = 1, Knight = 2, } //This returns a value that shown if the pawn can be placed safely public bool IsSafeToAddPawn(PawnType); public CareTaker This corresponds to caretaker of memento This is a double dimentional integer array that keeps a track of all states. The reason for having 2D array is to keep track of how many states are stored and which state is currently active. An example: 0 -2 1 -1 2 0 - This is current state. With second index 0/ 3 1 - This state has been saved, but has been undone private int [][]State; private ChessBoard [] MChessBoard; //This gets the chessboard at the position requested and assigns it to originator public ChessBoard GetChessBoard(int); //This overwrites the chessboard at given position public void SetChessBoard(ChessBoard, int); private int [][]State; public PlayGame (This is the originator) private bool status; private ChessBoard oChessBoard; //This sets the state of chessboard at position specified public SetChessBoard(ChessBoard, int); //This gets the state of chessboard at position specified public ChessBoard GetChessBoard(int); //This function tries to place both the pawns and returns the status of this attempt public bool PlacePawns(Pawn);

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• Is OOP hard because it is not natural?

  - by zvrba

  One can often hear that OOP naturally corresponds to the way people think about the world. But I would strongly disagree with this statement: We (or at least I) conceptualize the world in terms of relationships between things we encounter, but the focus of OOP is designing individual classes and their hierarchies. Note that, in everyday life, relationships and actions exist mostly between objects that would have been instances of unrelated classes in OOP. Examples of such relationships are: "my screen is on top of the table"; "I (a human being) am sitting on a chair"; "a car is on the road"; "I am typing on the keyboard"; "the coffee machine boils water", "the text is shown in the terminal window." We think in terms of bivalent (sometimes trivalent, as, for example in, "I gave you flowers") verbs where the verb is the action (relation) that operates on two objects to produce some result/action. The focus is on action, and the two (or three) [grammatical] objects have equal importance. Contrast that with OOP where you first have to find one object (noun) and tell it to perform some action on another object. The way of thinking is shifted from actions/verbs operating on nouns to nouns operating on nouns -- it is as if everything is being said in passive or reflexive voice, e.g., "the text is being shown by the terminal window". Or maybe "the text draws itself on the terminal window". Not only is the focus shifted to nouns, but one of the nouns (let's call it grammatical subject) is given higher "importance" than the other (grammatical object). Thus one must decide whether one will say terminalWindow.show(someText) or someText.show(terminalWindow). But why burden people with such trivial decisions with no operational consequences when one really means show(terminalWindow, someText)? [Consequences are operationally insignificant -- in both cases the text is shown on the terminal window -- but can be very serious in the design of class hierarchies and a "wrong" choice can lead to convoluted and hard to maintain code.] I would therefore argue that the mainstream way of doing OOP (class-based, single-dispatch) is hard because it IS UNNATURAL and does not correspond to how humans think about the world. Generic methods from CLOS are closer to my way of thinking, but, alas, this is not widespread approach. Given these problems, how/why did it happen that the currently mainstream way of doing OOP became so popular? And what, if anything, can be done to dethrone it?

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• USB drives not recognized all of a sudden (usb_storage not loaded lsmod does not report usb_storage)

  - by Siddharth

  I have tried most of the advice on askubuntu and other sites, usb_storage enable to fdisk -l. But I am unable to find steps to get it working again. sudo lsusb results Bus.... skipped 4 lines Bus 004 Device 002: ID 413c:3012 Dell Computer Corp. Optical Wheel Mouse Bus 005 Device 002: ID 413c:2105 Dell Computer Corp. Model L100 Keyboard Bus 001 Device 005: ID 8564:1000 sudo dmseg | tail reports [ 69.567948] usb 1-4: USB disconnect, device number 4 [ 74.084041] usb 1-6: new high-speed USB device number 5 using ehci_hcd [ 74.240484] Initializing USB Mass Storage driver... [ 74.256033] scsi5 : usb-storage 1-6:1.0 [ 74.256145] usbcore: registered new interface driver usb-storage [ 74.256147] USB Mass Storage support registered. [ 74.257290] usbcore: deregistering interface driver usb-storage fdisk -l reports Device Boot Start End Blocks Id System /dev/sda1 * 2048 972656639 486327296 83 Linux /dev/sda2 972658686 976771071 2056193 5 Extended /dev/sda5 972658688 976771071 2056192 82 Linux swap / Solaris I think I need steps to install and get usb_storage module working. Edit : I tried sudo modprobe -v usb-storage reports sudo modprobe -v usb-storage insmod /lib/modules/3.2.0-48-generic-pae/kernel/drivers/usb/storage/usb-storage.ko Edit : jsiddharth@siddharth-desktop:~$ sudo udevadm monitor --udev monitor will print the received events for: UDEV - the event which udev sends out after rule processing UDEV [4757.144372] add /module/usb_storage (module) UDEV [4757.146558] remove /module/usb_storage (module) UDEV [4757.148707] add /devices/pci0000:00/0000:00:1d.7/usb1/1-6 (usb) UDEV [4757.149699] add /bus/usb/drivers/usb-storage (drivers) UDEV [4757.151214] remove /bus/usb/drivers/usb-storage (drivers) UDEV [4757.156873] add /devices/pci0000:00/0000:00:1d.7/usb1/1-6/1-6:1.0 (usb) UDEV [4757.160903] add /devices/pci0000:00/0000:00:1d.7/usb1/1-6/1-6:1.0/host9 (scsi) UDEV [4757.164672] add /devices/pci0000:00/0000:00:1d.7/usb1/1-6/1-6:1.0/host9/scsi_host/host9 (scsi_host) UDEV [4757.165163] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-6/1-6:1.0/host9/scsi_host/host9 (scsi_host) UDEV [4757.165440] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-6/1-6:1.0/host9 (scsi) Narrowing down more : Seems like I need usb_storage to load as a module jsiddharth@siddharth-desktop:~$ lsmod | grep usb usbserial 37201 0 usbhid 41937 0 hid 77428 1 usbhid Still no usb driver mounted. Nor does a device show up in /dev. Any step by step process to debug and fix this will be really helpful.

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• Insufficient storage available to create shadow copy

  - by Bob.at.SBS

  I have used the "Windows 7 File Recovery" tool under Windows 8 to create system image backups to an external USB hard drive. I built a new Windows 8.1 machine, and I want to create my first system image backup of that machine to the same USB hard drive. The "Windows 7 File Recovery" tool is gone in Windows 8.1, but wbAdmin is alive and well: wbAdmin start backup -backupTarget:\\?\Volume{2a2b...994f} -allCritical -quiet fails with this text displayed: wbadmin 1.0 - Backup command-line tool (C) Copyright 2013 Microsoft Corporation. All rights reserved. Retrieving volume information... This will back up (EFI System Partition),(C:),Recovery (300.00 MB) to \?\Volume {2a2b1255-3a86-11e3-be86-b8ca3a83994f}. The backup operation to F: is starting. Creating a shadow copy of the volumes specified for backup... Summary of the backup operation: The backup operation stopped before completing. The backup operation stopped before completing. Detailed error: ERROR - A Volume Shadow Copy Service operation error has occurred: (0x8004231f) Insufficient storage available to create either the shadow copy storage file or other shadow copy data. The EFI System Partition is 100 MB The Recovery Partition is 300 MB The C partition is 1.72 TB, NTFS, 218 GB used, 1.51 TB free The destination drive is 1.81 TB, NTFS, 678 GB used, 1.15 TB free I've fiddled with vssadmin resize shadowstorage, with no change in the error. vssadmin list shadowstorage displays: Shadow Copy Storage association For volume: (C:)\?\Volume{37a0...263}\ Shadow Copy Storage volume: (C:)\?\Volume{37a0...263}\ Used Shadow Copy Storage space: 2.39 GB (0%) Allocated Shadow Copy Storage space: 2.81 GB (0%) Maximum Shadow Copy Storage space: 531 GB (30%) Shadow Copy Storage association For volume: (F:)\?\Volume{2a2...94f}\ Shadow Copy Storage volume: (F:)\?\Volume{2a2...94f}\ Used Shadow Copy Storage space: 334 GB (17%) Allocated Shadow Copy Storage space: 337 GB (18%) Maximum Shadow Copy Storage space: UNBOUNDED (922154758%) (Yeah, the "percent calculation" for UNBOUNDED is seriously bogus.) I've run SFC /verifyonly and it seems happy. I've verified that the new `Volume Shadow Copy" service starts when I start the backup operation. Any suggestions?

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• best storage option for recording live streaming video

  - by Alchemical

  We're creating a new web site that includes video chat capabilities. Wowza Server is being used for the streaming media. We would like the capability for users to record their video chats in certain circumstances. Is it feasible to record the videos to the same server running Wowza? Or performance-wise, would it make more sense to store them on another server? I understand SANs are popular as well, but I'm a little concerned about cost for those as we are on a fairly tight budget. Currently we have two servers with pretty decent RAID cnofigurations for storage, one has 14TB and the other 6TB. Mostly concerned if doing the recording on the same server as the streaming server (or web server), could significantly adversely affect that server's primary function.

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