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• Should I use mod_wsgi embedded mode if I have full control of Apache?

  - by mgibsonbr

  I'm managing a bunch of sites and applications in a shared hosting, using Django via mod_wsgi. I had planned to use daemon mode from the beginning (to avoid restart problems), but ended up purchasing a plan that allows me to run a dedicated Apache instance. I kept using daemon mode for convenience, but I'm afraid it's consuming more server resources than it should (I have different projects for each site, each with its own process and process group), so I'm considering switching to embedded mode. Would that be a sensible thing to do? I'd still be able to restart Apache anytime I need to, and I wouldn't need so many child processes and sockets (so I hope the resource usage would decrease). But I'm unsure whether or not doing so would make it more difficult to manage those sites (if I need to update one, I have to restart all) or maybe the applications won't be properly isolated from one another. Are these problems really significant (or only a minor nuisance), are there other drawbacks I coudn't foresee? I'm looking for advice in any aspect of this setup - mainainability, performance, security etc. Tips for improving the current setup are also welcome (I know how to correctly configure a basic mod_wsgi setup, but I'm clueless about sensible values for threads, processes etc).

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• How to maximise performance in computers connected into LAN via Gigabit ethernet router?

  - by penyuan

  Our group is setting up a server (which might just be a NAS, but we're not sure yet), which shares files, so that it connects to all other computers in the room (about 10 of them). I am thinking just hooking all of them up via a gigabit router/switch. Is there anything I should watch out for, in terms of cables, connections, or the connection capabilities of each computer in the network? For instance, I don't want a slow computer in the LAN to slow down everyone else's connection, etc., etc. Thanks for the education.

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• Data Transformation Pipeline

  - by davenewza

  I have create some kind of data pipeline to transform coordinate data into more useful information. Here is the shell of pipeline: public class PositionPipeline { protected List<IPipelineComponent> components; public PositionPipeline() { components = new List<IPipelineComponent>(); } public PositionPipelineEntity Process(Position position) { foreach (var component in components) { position = component.Execute(position); } return position; } public PositionPipeline RegisterComponent(IPipelineComponent component) { components.Add(component); return this; } } Every IPipelineComponent accepts and returns the same type - a PositionPipelineEntity. Code: public interface IPipelineComponent { PositionPipelineEntity Execute(PositionPipelineEntity position); } The PositionPipelineEntity needs to have many properties, many which are unused in certain components and required in others. Some properties will also have become redundant at the end of the pipeline. For example, these components could be executed: TransformCoordinatesComponent: Parse the raw coordinate data into a Coordinate type. DetermineCountryComponent: Determine and stores country code. DetermineOnRoadComponent: Determine and store whether coordinate is on a road. Code: pipeline .RegisterComponent(new TransformCoordinatesComponent()) .RegisterComponent(new DetermineCountryComponent()) .RegisterComponent(new DetermineOnRoadComponent()); pipeline.Process(positionPipelineEntity); The PositionPipelineEntity type: public class PositionPipelineEntity { // Only relevant to the TransformCoordinatesComponent public decimal RawCoordinateLatitude { get; set; } // Only relevant to the TransformCoordinatesComponent public decimal RawCoordinateLongitude { get; set; } // Required by all components after TransformCoordinatesComponent public Coordinate CoordinateLatitude { get; set; } // Required by all components after TransformCoordinatesComponent public Coordinate CoordinateLongitude { get; set; } // Set in DetermineCountryComponent, not required anywhere. // Requires CoordinateLatitude and CoordinateLongitude (TransformCoordinatesComponent) public string CountryCode { get; set; } // Set in DetermineOnRoadComponent, not required anywhere. // Requires CoordinateLatitude and CoordinateLongitude (TransformCoordinatesComponent) public bool OnRoad { get; set; } } Problems: I'm very concerned about the dependency that a component has on properties. The way to solve this would be to create specific types for each component. The problem then is that I cannot chain them together like this. The other problem is the order of components in the pipeline matters. There is some dependency. The current structure does not provide any static or runtime checking for such a thing. Any feedback would be appreciated.

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• Best way to remote restart Ubuntu from Windows machine

  - by robsoft

  Background: I'm looking to put a series of Ubuntu machines into retail locations, they're being used as dumb kiosks to show a series of slides onto large LCD panel TV screens. Once installed, they won't have a keyboard or mouse connected but will have a fixed IP on the local network. Everything is configured to auto-start, no automatic updates, no power saving etc - I think we're pretty-much good to go apart from one thing. I need the retail staff to be able to restart the boxes if a problem arises. We have VNC running (now that we've turned off desktop enhancements!) so that we can remotely get into the machines if we need to, but that's not something we would allow the retail staff to do. The machines are going to be physically 'out of the way' (probably in the ceiling space) so the power button is not easily accessible!. I'd like to have some means of allowing the retail staff to restart the Ubuntu machine, from the desktop of one of their Windows terminals. I don't really want to give them some kind of raw terminal access (the command line will frighten them!) and I don't want them to use VNC (as stated above). Ideally there would be an icon on the Windows desktop, they double-click it, reply to a simple 'are you sure?' prompt, and then the Ubuntu box is told to restart. The Windows side of that won't be a problem, we can write something using Delphi, Python & Qt4, whatever - it's the Ubuntu side of it I'm stuck with. Out of sight/view, could I have a Windows program open a terminal across the network and tell Ubuntu to restart? Is this what SSH could be used for (I have never set that kind of thing up). The Windows programming side isn't really an issue, it's just that I'm a total Ubuntu noob and don't know where to start from the platform point of view. The other thing we considered is also having the machine automatically restart itself at a set time each day (obviously out of store hours!). To me, that seems a bit unnecessary (though forcing a restart once a week/month might be worthwhile). Any thoughts or suggestions? Being able to restart the box on demand across the network is my prime requirement.

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• OpenOffice Calc: How can I count the number of different items with data pilot?

  - by manu

  Hi all, I have a rather long spreadsheet with historical information of issues solved by some user on a colaborative environment. The spreadsheet have the following (relevant) columns date, week no., project, author id, etc... The week no. is calculated from the date, is basically the year concatenated with the week number within that year; for instance, both 2009-02-18 and 2009-02-20 yield the week number 200908 - the 8th week of year 2009; and 2009-02-23 yields 200909 - the 9th week of year 2009. I need to count how many different users (given by author id) contributed to some project, on a weekly basis. I have setup a data pilot with the week as Row Field, the project as the Column Field, and count-author as the Data Field. However, this counts the author id as different instances. This is not what I need. I need to count how many different users contributed to each project on a weekly basis. I expect to get something like: projects week Project1 Project2 Project3 200901 10 2 200902 2 7 Each inner cell containing how many different users contributed. With the count-author configuration, what I get is how many contributions (total) got the project on that week. Is there a way to tell OpenOffice Calc to do what I want?

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• Are there any concerns with using a static read-only unit of work so that it behaves like a cache?

  - by Rowan Freeman

  Related question: How do I cache data that rarely changes? I'm making an ASP.NET MVC4 application. On every request the security details about the user will need to be checked with the area/controller/action that they are accessing to see if they are allowed to view it. The security information is stored in the database. For example: User Permission UserPermission Action ActionPermission A "Permission" is a token that is applied to an MVC action to indicate that the token is required in order to access the action. Once a user is given the permission (via the UserPermission table) then they have the token and can therefore access the action. I've been looking in to how to cache this data (since it rarely changes) so that I'm only querying in-memory data and not hitting a database (which is a considerable performance hit at the moment). I've tried storing things in lists, using a caching provider but I either run in to problems or performance doesn't improve. One problem that I constantly run in to is that I'm using lazy loading and dynamic proxies with EntityFramework. This means that even if I ToList() everything and store them somewhere static, the relationships are never populated. For example, User.Permissions is an ICollection but it's always null. I don't want to Include() everything because I'm trying to keep things simple and generic (and easy to modify). One thing I know is that an EntityFramework DbContext is a unit of work that acts with 1st-level caching. That is, for the duration of the unit of work, everything that is accessed is cached in memory. I want to create a read-only DbContext that will exist indefinitely and will only be used to read about permission data. Upon testing this it worked perfectly; my page load times went from 200ms+ to 20ms. I can easily force the data to refresh at certain intervals or simply leave it to refresh when the application pool is recycled. Basically it will behave like a cache. Note that the rest of the application will interact with other contexts that exist per request as normal. Is there any disadvantage to this approach? Could I be doing something different?

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• UPDATE FOR BI PUBLISHER ENTERPRISE 10.1.3.4.2 NOVEMBER 2011

  - by Tim Dexter

  It's Friday, that means its patch release time. Why do we do this to ourselves, 'we'll release on Friday!' It might 11.59 on Friday but by golly we'll have released on Friday. I can remember a release of BIP years ago that for some reason we went for 12/31 as a release date ... were we mad? I seem to remember we made it but talk about ridiculous pressure! The latest 10g rollup is out in the wild and available from Oracle support. A bug fixing rollup but worth getting to and know that support will want you to get to it and re-test before going forward on an SR. One simple but very useful fix or enhancement:[Cause of the bug] @ ================== @ Customer reports that despite the clock being shown, end users are clicking @ on the View button repeatedly as the initial generation is taking some time.   @ If the button were to be grayed out then  this would prevent the users @ requesting the report more than  once.  Repeated requests are causing a @ system overload and as this is their Production  instance this is extremely @ important to the customer. @ . @ [The Fix] @ ========= @ Added the logic to disable the button after the user clicks on the "view" @ button and re-enable it when the report is loaded. I told a group of customers once that they have a headache and we have a non-steroidal anti-inflammatory drug, alright, I actually said 'aspirin'. This little gem of a fix helps relieve another little headache that our aspirin was causing. The patch number for all this BIP pain killing is 13399232, enjoy!

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• Tomcat log include servlet context

  - by Kris

  I have a Tomcat instance running several websites. Recently I've been trying to deal with the various error messages that wind up in the Tomcat log file (catalina.out). None of the issues are affecting the websites, but all the noise is making it difficult to see actual problems. My problem is that frequently the message is being emitted by a library that is used by multiple webapps. Unless a stacktrace is included (which it often isn't) I can't tell which webapp is responsible without a lot of digging. So the question is, can I somehow configure Tomcat to include the servlet context in the log file? Or perhaps have different log files per context?

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• Indentation-based Folding for TextMate

  - by Craig Walker

  SASS and HAML have indentation-based syntax, much like Python. Blocks of related code have the same number of spaces at the start of a line. Here's some example code: #drawer height: 100% color: #c2c7c4 font: size: 10px .slider overflow: hidden height: 100% .edge background: url('/images/foo') repeat-y .tab margin-top = !drawer_top width: 56px height: 161px display: block I'm using phuibonhoa's SASS bundle, and I'd like to enhance it so that the various sections can fold. For instance, I'd like to fold everything under #drawer, everything under .slider, everything under .edge, etc. The bundle currently includes the following folding code: foldingStartMarker = '/\*|^#|^\*|^\b|^\.'; foldingStopMarker = '\*/|^\s*$'; How can I enhance this to fold similarly-indented blocks?

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• How to move selection in Excel?

  - by John van der Laan

  I know how to create or extend selections, i.e., via F8 or Shift F8. When I have created the desired selection, I would like to move that particular selection a few cells to the right and/or down. I now need to select the similar form selection on another place in the worksheet. Does anyone know how I can do this? Example: Selection made on A1..B3, C3 and D5 and, for instance, made it Yellow. I now want to move this complete selection four places to the right, to E1..F3, H3 and I5 (to be able to make it another color). It has nothing to do with the cut and paste to move cells.

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• Reinventing the Wheel, why should I?

  - by Mercfh

  So I have this problem, it may be my OCD (i have OCD it's not severe.....but It makes me very..lets say specific about certain things, programming being one of them) or it may be the fact that I graduated college and still feel "meh" at programming. Reading This made me think "OH thats me!" but thats not really my main problem. My big problem is....anytime im using a high level language/API/etc. I always think to myself that im not really "programming". I know I know...it sounds stupid. But Like I feel like....if i can't figure out how to do it at the lowest level then Im not really "understanding" it. I do this for just about every new technology I learn. I look at the lowest level and try to understand it. Sometimes I do.....most of the time I don't, I mean i've only really been programming for 4 years (at college, if you even call it programming.....our university's program was "meh"). For instance I do a little bit of embedded programming (with the Atmel AVR 8bits/Arduino stuff). And I can't bring myself to use the C compiler, even though it's 8 million times easier than using assembly......it's stupid I know... Anyone else feel like this, I think it's just my OCD that makes me feel this way....but has anyone else ever felt like they need to go down to the lowest level of the language to even be satisfied with using it? I apologize for the very very odd question, but I think it really hinders me in getting deep seeded into a programming language and making a real application of my own. (it's silly I know)

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• Need to re-build an application - how?

  - by Tom

  For our main system, we have a small monitor application that sits outside our network and periodically tries to log in to verify the system still works. We have a problem with the monitor though in that the communications component set (Asta 3 inside Delphi applications) doesn't always connect through. Overall, I'd say it's about 95% reliable, but that other 5% kills the monitor since it will try to log in and hang on the connection attempt (no timeout in the component). This really isn't an issue on the client side of the system since the clients don't disconnect and reconnect repeatedly on the same application instance, but I need a way to make sure the monitor stays up and continues working even when the component fails on a run. I have a few ideas as to which way to have the program run, the main idea being to put the communications inside a threaded data module so that if one thread crashes then another thread can test later and the program keep going. Does this sound like a valid way to go? Any other ideas how to ensure a reliable monitoring application with a less than 100% reliable component? Thanks. P.S. Not sure these tags are the most appropriate. Tried including "system-reliability" as one, but not high enough rep to create.

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• Which JMX statistics to watch out for in Catalina/Tomcat?

  - by geoaxis

  I have configured OpenNMS to collect all kinds of numeric data coming out of tomcat7 jmx. There are a lot of things. I am interested in monitoring this tomcat instance so that I can avoid down time and lockups. What metrics should I be watching out for? I am already monitoring things like CPU, Memory, Network via SNMP. With this JMX connection the things that I find interesting are Catalina:type=GlobalRequestProcessor,name="ajp-bio-/a.b.c.d-XXXX" RequestsCount so far. Catalina:type=Manager,context=/myApp,host=localhost Active sessions and its maximum so far

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• Is MongoDB a good choice or not for my application?

  - by shubham

  I have a Reporting application which stores the reports in xml format as recieved from source (XML schema is not defined, it can be any format) and those reports contain some keys and values. Like jobid, setid be keys for 1 type of report and userid, groupId for another type of report etc. The type of keys that can be referred from the document is determined by the namespaces used in the xml doc. These keys are stored on the basis of namespace used in the xml document. For e.g. If a tag in xml fragment uses namespace= "myspace1", then I have keys A and B for myspace1 stored in another table. It will fetch those keys from that table for this namespace, look for their values in xml doc and store it in another table along with the pointer to this xml document (Id of a record storing complete xml document in a cell). Use cases: When the user comes and queries for that key and value, I return the document or a set of documents that are having those key/value pairs. When the user comes and queries for a certain key and provide a name for xslt (pre stored), I fetch the set of documents fulfilling that criteria and convert that xml to html with the specified xslt. When the user comes and asks for a particular fragment of a doc then it can fetch a subset from a particular document also. When the user comes and queries for top x values of a certain key, I return the set of documents that are having top 10 values of that key. I am using DB2 database for its support of xml along with relational capabilities. That makes easier for me to run xpath expressions and fetch values of keys and also aggregate a set of documents fullfilling a criteria, all on the database side. Problems: DB2 stores XML doc of upto 2GB in size. Retrieval is very slow. If some thing involves many documents, then it takes significant time for things to show up in browser, and the user has to wait. Can MongoDb help in this case, as it is document oriented? can I do xml related xpath queries and document transformations on db side? Or is it ok to use both in such a case?

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• What is a good strategy for binding view objects to model objects in C++?

  - by B.J.

  Imagine I have a rich data model that is represented by a hierarchy of objects. I also have a view hierarchy with views that can extract required data from model objects and display the data (and allow the user to manipulate the data). Actually, there could be multiple view hierarchies that can represent and manipulate the model (e.g. an overview-detail view and a direct manipulation view). My current approach for this is for the controller layer to store a reference to the underlying model object in the View object. The view object can then get the current data from the model for display, and can send the model object messages to update the data. View objects are effectively observers of the model objects and the model objects broadcast notifications when properties change. This approach allows all the views to update simultaneously when any view changes the model. Implemented carefully, this all works. However, it does require a lot of work to ensure that no view or model objects hold any stale references to model objects. The user can delete model objects or sub-hierarchies of the model at any time. Ensuring that all the view objects that hold references to the model objects that have been deleted is time-consuming and difficult. It feels like the approach I have been taking is not especially clean; while I don't want to have to have explicit code in the controller layer for mediating the communication between the views and the model, it seems like there must be a better (implicit) approach for establishing bindings between the view and the model and between related model objects. In particular, I am looking for an approach (in C++) that understands two key points: There is a many to one relationship between view and model objects If the underlying model object is destroyed, all the dependent view objects must be cleaned up so that no stale references exist While shared_ptr and weak_ptr can be used to manage the lifetimes of the underlying model objects and allows for weak references from the view to the model, they don't provide for notification of the destruction of the underlying object (they do in the sense that the use of a stale weak_ptr allows for notification), but I need an approach that notifies the dependent objects that their weak reference is going away. Can anyone suggest a good strategy to manage this?

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• The best way to learn how to extend Orchard

  - by Bertrand Le Roy

  We do have tutorials on the Orchard site, but we can't cover all topics, and recently I've found myself more and more responding to forum questions by pointing people to an existing module that was solving a similar problem to the one the question was about. I really like this way of learning by example and from the expertise of others. This is one of the reasons why we decided that modules would by default come in source code form that we compile dynamically. it makes them easy to understand and easier to modify for your own purposes. Hackability FTW! But how do you crack open a module and look at what's inside? You can do it in two different ways. First, you can just install the module from the gallery, directly from your Orchard instance's admin panel. Once you've done that, you can just look into your Modules directory under the web site. There is now a subfolder with the name of the new module that contains a csproj that you can open in Visual Studio or add to your Orchard solution. Second, you can simply download the package (it's NuGet) and rename it to a .zip extension. NuGet being based on Zip, this will open just fine in Windows Explorer: What you want to dig into is the Content/Modules/[NameOfTheModule] folder, which is where the actual code is. Thanks to Jason Gaylord for the idea for this post.

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• Setting up a SQL server outside the domain

  - by user12391

  Hi, im very new to this. I've set up an account "SQLBOX" thats on the a network, but not connected to the domain. I have installed an instance of SQL Server 2008 and am trying to connect to it from another machine on the network but am getting "Cannot connect to "SQLBOX"". From the "SQLBOX" i can connect to sqlservers on the domain, but not vice-versa. Any help would be greatly appreciated. Sorry if the description isn't great. EDIT I can ping the box from a machine on the domain

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• Demantra Implementation Tip Windows and Unix or Linux

  - by user702295

  Hello!  Are you implementing using a third party or consulting resources?   Recently we have seen some cases where customers no longer have a windows installation.  After the initial install and configuration, once the instance has gone live, the windows install is either deleted or most likely no longer with the customer as the same was installed on the implementers' laptop to start with. As a result when support comes back requesting the customer to apply a patch and/or upgrade they do not have a windows installation.  This has started happening after Oracle Demantra gave them the option to configure the engine on Unix.  Workaround: It is advisable that the customer keep their Windows installation intact for further patching and/or upgrade.  It is aslo possible that the implementer had installed Demantra on his Windows box and you do not have access to it any more.  It is possible that with the web and engine on Unix, and the silent installer having downloaded all the executable for Business Modeler, to work on the User's client machine, you may no longer need the windows install. I have not tested the above 

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• Linking Libraries in iOS?

  - by Bob Dole

  This is probably a totally noob question but I have missing links in my mind when thinking about linking libraries in iOS. I usually just add a new library that's been cross compiled and set the build and linker paths without really know what I'm doing. I'm hoping someone can help me fill in some gaps. Let's take the OpenCV library for instance. I have this totally working btw because of a really well written tutorial( http://niw.at/articles/2009/03/14/using-opencv-on-iphone/en ), but I'm just wanting to know what is exactly going on. What I'm thinking is happening is that when I build OpenCV for iOS is that your creating object code that gets placed in the .a files. This object code is just the implementation files( .m ) compiled. One reason you would want to do this is to make it hard to see the source code and so that you don't have to compile that source code every time. The .h files won't be put in the library ( .a ). You include the .h in your source files and these header files communicate with the object code library ( .a ) in some way. You also have to include the header files for your library in the Build Path and the Library itself in the Linker Path. So, is the way I view linking libraries correct? If , not can someone correct me on this ?

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• Hijacking ASP.NET Sessions

  - by Ricardo Peres

  So, you want to be able to access other user’s session state from the session id, right? Well, I don’t know if you should, but you definitely can do that! Here is an extension method for that purpose. It uses a bit of reflection, which means, it may not work with future versions of .NET (I tested it with .NET 4.0/4.5). 1: public static class HttpApplicationExtensions 2: { 3: private static readonly FieldInfo storeField = typeof(SessionStateModule).GetField("_store", BindingFlags.NonPublic | BindingFlags.Instance); 4:  5: public static ISessionStateItemCollection GetSessionById(this HttpApplication app, String sessionId) 6: { 7: var module = app.Modules["Session"] as SessionStateModule; 8:  9: if (module == null) 10: { 11: return (null); 12: } 13:  14: var provider = storeField.GetValue(module) as SessionStateStoreProviderBase; 15:  16: if (provider == null) 17: { 18: return (null); 19: } 20:  21: Boolean locked; 22: TimeSpan lockAge; 23: Object lockId; 24: SessionStateActions actions; 25:  26: var data = provider.GetItem(HttpContext.Current, sessionId.Trim(), out locked, out lockAge, out lockId, out actions); 27:  28: if (data == null) 29: { 30: return (null); 31: } 32:  33: return (data.Items); 34: } 35: } As you can see, it extends the HttpApplication class, that is because we need to access the modules collection, for the Session module. Use with care!

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• About shared (static) Members and its behavior

  - by Allende

  I just realized that I can access shared members from instances of classes (probably this is not correct, but compile and run), and also learn/discover that, I can modify shared members, then create a new instance and access the new value of the shared member. My question is, what happens to the shared members, when it comes back to the "default" value (class declaration), how dangerous is it do this ? is it totally bad ? is it valid in some cases ?. If you want to test my point here is the code (console project vb.net) that I used to test shared members, as you can see/compile/run, the shared member "x" of the class "Hello" has default value string "Default", but at runtime it changes it, and after creating a new object of that class, this object has the new value of the shared member. Module Module1 Public Class hello Public Shared x As String = "Default" Public Sub New() End Sub End Class Sub Main() Console.WriteLine("hello.x=" & hello.x) Dim obj As New hello() Console.WriteLine("obj.x=" & obj.x) obj.x = "Default shared memeber, modified in object" Console.WriteLine("obj.x=" & obj.x) hello.x = "Defaul shared member, modified in class" Console.WriteLine("hello.x=" & hello.x) Dim obj2 As New hello() Console.WriteLine("obj2.x=" & obj2.x) Console.ReadLine() End Sub End Module UPDATE: First at all, thanks to everyone, each answer give feedback, I suppose, by respect I should choose one as "the answer", I don't want to be offensive to anyone, so please don't take it so bad if I didn't choose you answer.

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• Where are ghostscript options / switches documented?

  - by sdaau

  I know there is a Ghostscript option, for instance -dPDFSETTINGS=/screen - where is that documented? How can I see what other options it accepts, appart from screen? Also, -dMaxSubsetPct=100 - what does it do? I open man gs, search for PDFSET, I get "Pattern not found". I type in a search engine, I get a myriad of personal webpages, no documentation hits. Can anyone help with a link? Many thanks in advance, Cheers! EDIT: also see this related post: Querying Ghostscript for the default options/settings of an output device (such as 'pdfwrite' or 'tiffg4') - Stack Overflow ... for getting a list of supported options for a given device.

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• Hadoop, NOSQL, and the Relational Model

  - by Phil Factor

  (Guest Editorial for the IT Pro/SysAdmin Newsletter)Whereas Relational Databases fit the world of commerce like a glove, it is useless to pretend that they are a perfect fit for all human endeavours. Although, with SQL Server, we’ve made great strides with indexing text, in processing spatial data and processing markup, there is still a problem in dealing efficiently with large volumes of ephemeral semi-structured data. Key-value stores such as Cassandra, Project Voldemort, and Riak are of great value for ephemeral data, and seem of equal value as a data-feed that provides aggregations to an RDBMS. However, the Document databases such as MongoDB and CouchDB are ideal for semi-structured data for which no fixed schema exists; analytics and logging are obvious examples. NoSQL products, such as MongoDB, tackle the semi-structured data problem with panache. MongoDB is designed with a simple document-oriented data model that scales horizontally across multiple servers. It doesn’t impose a schema, and relies on the application to enforce the data structure. This is another take on the old ‘EAV’ problem (where you don’t know in advance all the attributes of a particular entity) It uses a clever replica set design that allows automatic failover, and uses journaling for data durability. It allows indexing and ad-hoc querying. However, for SQL Server users, the obvious choice for handling semi-structured data is Apache Hadoop. There will soon be an ODBC Driver for Apache Hive .and an Add-in for Excel. Additionally, there are now two Hadoop-based connectors for SQL Server; the Apache Hadoop connector for SQL Server 2008 R2, and the SQL Server Parallel Data Warehouse (PDW) connector. We can connect to Hadoop process the semi-structured data and then store it in SQL Server. For one steeped in the culture of Relational SQL Databases, I might be expected to throw up my hands in the air in a gesture of contempt for a technology that was, judging by the overblown journalism on the subject, about to make my own profession as archaic as the Saggar makers bottom knocker (a potter’s assistant who helped the saggar maker to make the bottom of the saggar by placing clay in a metal hoop and bashing it). However, on the contrary, I find that I'm delighted with the advances made by the NoSQL databases in the past few years. Having the flow of ideas from the NoSQL providers will knock any trace of complacency out of the providers of Relational Databases and inspire them into back-fitting some features, such as horizontal scaling, with sharding and automatic failover into SQL-based RDBMSs. It will do the breed a power of good to benefit from all this lateral thinking.

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• How do I customize zsh's vim mode?

  - by Jason Baker

  Ok, so I finally made the great change. In my .zshenv, I changed my EDITOR: export EDITOR=vim There are a couple of questions I have that are so minor that I didn't want to start separate questions for them. Here they are: How do I get zsh to distinguish between insert mode and command mode like in vim? Preferably this would change the cursor from an underline to a block like in vim, but displaying text at the bottom would work as well. How do I get it to act more like vim? For instance, I'd rather it be in command mode by default and not go out of it after one command.

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• Why are some PNGs open in Photoshop with Indexed Colors and no transparency?

  - by Daniel Beardsley

  Why are some 32 bit PNGs opened in Photoshop with Indexed Colors and no transparency? For instance, I grabbed a png icon file of the Stack Overflow logo at: http://blog.stackoverflow.com/wp-content/uploads/icon-so.png When opening it in Photoshop CS3, it apparently treats it as indexed color and gets rid of the alpha channel. The image on the right is a screen grab of the icon. Changing the Image mode in Photoshop to RGB doesn't change the image at all. I've tried this with a few other PNGs and it seems hit or miss. When viewed in other programs, it displays fine. left:png opened in Photoshop, right:screen grab of png from browser What gives?, does Photoshop not interpret the PNG file format correctly?

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