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• Virtual Lan on the Cloud -- Help Confirm my understanding?

  - by marfarma

  [Note: Tried to post this over at ServerFault, but I don't have enough 'points' for more than one link. Powers that be, move this question over there.] Please give this a quick read and let me know if I'm missing something before I start trying to make this work. I'm not a systems admin professional, and I'd hate to end up banging my head into the wall if I can avoid it. Goals: Create a 'road-warrior' capable star shaped virtual LAN for consultants who spend the majority of their time on client sites, and who's firm has no physical network or servers. Enable CIFS access to a cloud-server based installation of Alfresco Allow Eventual implementation of some form of single-sign-on ( OpenLDAP server ) access to Alfresco and other server applications implemented in the future Given: All Servers will live in the public internet cloud (Rackspace Cloud Servers) OpenVPN Server will be a Linux disto, probably Ubuntu 9.x, installed on same server as Alfresco (at least to start) Staff will access server applications and resources from client sites, hotels, trains, planes, coffee shops or their homes over various ISP, using their company laptops or personal home desktops. Based on my Research thus far, to accomplish this, I'll need: OpenVPN with Bridging Enabled to create a star shaped "virtual" LAN http://openvpn.net/index.php/open-source/documentation/miscellaneous/76-ethernet-bridging.html A Road Warrior Network Configuration, as described in this Shorewall article (lower down the page) http://www.shorewall.net/OPENVPN.html Configure bridge addressesing (probably DHCP) http://openvpn.net/index.php/open-source/faq.html#bridge-addressing Configure CIFS / Samba to accept VPN IP address http://serverfault.com/questions/137933/howto-access-samba-share-over-vpn-tunnel Set up Client software, with keys configured for access (potentially through a OpenVPN-Sa client portal) http://www.openvpn.net/index.php/access-server/download-openvpn-as/221-installation-overview.html

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• Parent Control Mouse Enter/Leave Events With Child Controls

  - by Paul Williams

  I have a C# .NET 2.0 WinForms app. My app has a control that is a container for two child controls: a label, and some kind of edit control. You can think of it like this, where the outer box is the parent control: +---------------------------------+ | [Label Control] [Edit Control] | +---------------------------------+ I am trying to do something when the mouse enters or leaves the parent control, but I don't care if the mouse moves into one of its children. I want a single flag to represent "the mouse is somewhere inside the parent or children" and "the mouse has moved outside of the parent control bounds". I've tried handling MouseEnter and MouseLeave on the parent and both child controls, but this means the action begins and ends multiple times as the mouse moves across the control. In other words, I get this: Parent.OnMouseEnter (start doing something) Parent.OnMouseLeave (stop) Child.OnMouseEnter (start doing something) Child.OnMouseLeave (stop) Parent.OnMouseEnter (start doing something) Parent.OnMouseLeave (stop) The intermediate OnMouseLeave events cause some undesired effects as whatever I'm doing gets started and then stopped. I want to avoid that. I don't want to capture the mouse as the parent gets the mouse over, because the child controls need their mouse events, and I want menu and other shortcut keys to work. Is there a way to do this inside the .NET framework? Or do I need to use a Windows mouse hook?

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• Reliable strtotime() result for different languages

  - by Maksee

  There was always a strange bug in Joomla when adding new article with back-end displayed with a language other than English (for me it's Russian). The field "Finish Publishing" started to be current date instead of "Never" equivalent in Russian. For a site in php4 finally found that strtotime function returns different results for arbitrary words. For "Never" it always -1 and joomla relies on this result in the JDate implementation. But in other case it sometimes returns a valid date. For russian translation of Never (???????) it is the case, but also for single "N" it is the case, so if one decided to change the string to some other he or she would face the same issue. So the code below <?php echo "Res:".strtotime("N")."<br>"; echo "Res:".strtotime("Nev")."<br>"; echo "Res:".strtotime("Neve")."<br>"; echo "Res:".strtotime("Never")."<br>"; ?> Outputs: Res:1271120400 Res:-1 Res:-1 Res:-1 So what are the solutions would be in this case? I would like not to write language-specific date.php handler, but to modify date method of JDate class, but what are language-neutral changes would be in order to detect invalid string. Thank you

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• Newbie python error in regards to import

  - by TylerW

  Hello. I'm a python newbie and starting out with using the Bottle web framework on Google App Engine. I've been messing with the super small, super easy Hello World sample and have already ran into problems. Heh. I finally got the code to work with this... import bottle from bottle import route from google.appengine.ext.webapp import util @route('/hello') def hello(): return "Hello World!" util.run_wsgi_app(bottle.default_app()) My question is, I thought I could just go 'import bottle' without the second line. But if I take the second line out, I get a NameError. Or if I do 'from bottle import *', I still get the error. bottle is just a single file called 'bottle.py' in my site's root directory. So neither of these work.... import bottle from google.appengine.ext.webapp import util @route('/hello') def hello(): return "Hello World!" util.run_wsgi_app(bottle.default_app()) Or from bottle import * from google.appengine.ext.webapp import util @route('/hello') def hello(): return "Hello World!" util.run_wsgi_app(bottle.default_app()) The error message I get is... Traceback (most recent call last): File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/tools/dev_appserver.py", line 3180, in _HandleRequest self._Dispatch(dispatcher, self.rfile, outfile, env_dict) File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/tools/dev_appserver.py", line 3123, in _Dispatch base_env_dict=env_dict) File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/tools/dev_appserver.py", line 515, in Dispatch base_env_dict=base_env_dict) File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/tools/dev_appserver.py", line 2382, in Dispatch self._module_dict) File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/tools/dev_appserver.py", line 2292, in ExecuteCGI reset_modules = exec_script(handler_path, cgi_path, hook) File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/tools/dev_appserver.py", line 2188, in ExecuteOrImportScript exec module_code in script_module.dict File "/Users/tyler/Dropbox/sites/dietgrid/code2.py", line 4, in @route('/hello') NameError: name 'route' is not defined So am I wrong in thinking it should be able to work the other ways or no?

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• Linq to sql DataContext cannot set load options after results been returned

  - by David Liddle

  I have two tables A and B with a one-to-many relationship respectively. On some pages I would like to get a list of A objects only. On other pages I would like to load A with objects in B attached. This can be handled by setting the load options DataLoadOptions options = new DataLoadOptions(); options.LoadWith<A>(a => a.B); dataContext.LoadOptions = options; The trouble occurs when I first of all view all A's with load options, then go to edit a single A (do not use load options), and after edit return to the previous page. I understand why the error is occurring but not sure how to best get round this problem. I would like the DataContext to be loaded up per request. I thought I was achieving this by using StructureMap to load up my DataContext on a per request basis. This is all part of an n-tier application where my Controllers call Services which in turn call Repositories. ForRequestedType<MyDataContext>() .CacheBy(InstanceScope.PerRequest) .TheDefault.Is.Object(new MyDataContext()); ForRequestedType<IAService>() .TheDefault.Is.OfConcreteType<AService>(); ForRequestedType<IARepository>() .TheDefault.Is.OfConcreteType<ARepository>(); Here is a brief outline of my Repository public class ARepository : IARepository { private MyDataContext db; public ARepository(MyDataContext context) { db = context; } public void SetLoadOptions(DataLoadOptions options) { db.LoadOptions = options; } public IQueryable<A> Get() { return from a in db.A select a; } So my ServiceLayer, on View All, sets the load options and then gets all A's. On editing A my ServiceLayer should spin up a new DataContext and just fetch a list of A's. When sql profiling, I can see that when I go to the Edit page it is requesting A with B objects.

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• Semantic Grid System, Media Query issue

  - by Andy

  I'm using the Semantic Grid System to build a responsive site. However, something isn't quite right with the media queries that should obviously kick in once it hits a particular screen size. I'll reference what i mean with their example on the website : if I view this on my iPhone for example, given that it is supposed to adjust to a single column structure on a mobile device, it still throws out the web version of the page. That is true for both Safari and Chrome on my iPhone. However, if I use the RWD bookmarklet to check it's appearance at different resolutions it appears as expected for the mobile resolution. Also, ironically, if I resize the page in Safari on my desktop it also adjusts accordingly once I get down to the approriate screen size, but not in Firefox. The media query that it uses once it hits 720px is @media screen and (max-width: 720px) { #maincolumn, #sidebar { .column(12); margin-bottom: 1em; } } and I might be wide of the mark here but I think that must be the issue. But given that this is directly from the semantic.gs website I'm not inclined to question their own code. Any idea what the problem might be?

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• How to explain to someone that a data structure should not draw itself, explaining separation of con

  - by leeand00

  I have another programmer who I'm trying to explain why it is that a UI component should not also be a data-structure. For instance say that you get a data-structure that contains a record-set from the "database", and you wish to display that record-set in a UI component within your application. According to this programmer (who will remain nameless, he's young and I'm teaching him...), we should subclass the data-structure into a class that will draw the UI component within our application!!!!!! And thus according to this logic, the record-set should manage the drawing of the UI. **Head Desk*** I know that asking a record-set to draw itself is wrong, because, if you wish to render the same data-structure on more than one type of component on your UI, you are going to have a real mess on your hands; you'll need to extend yet another class for each and every UI component that you render from the base-class of your record-set; I am well aware of the "cleanliness" of the of the MVC pattern (and by that what I really mean is you don't confuse your data (the Model) with your UI (the view) or the actions that take place on the data (the Controller more or less...okay not really the API should really handle that...and the Controller should just make as few calls to it as it can, telling it which view to render)) But it's certainly alot cleaner than using data-structures to render UI components! Is there any other advice I could send his way other than the example above? I understand that when you first learn OOP you go through "a stage" where you where just want to extend everything. Followed by a stage when you think that Design Patterns are the solution every single problem...which isn't entirely correct either...thanks Jeff. Is there a way that I can gently nudge this kid in the right direction? Do you have any more examples that might help explain my point to him?

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• Reading CSV files in numpy where delimiter is ","

  - by monch1962

  Hello all, I've got a CSV file with a format that looks like this: "FieldName1", "FieldName2", "FieldName3", "FieldName4" "04/13/2010 14:45:07.008", "7.59484916392", "10", "6.552373" "04/13/2010 14:45:22.010", "6.55478493312", "9", "3.5378543" ... Note that there are double quote characters at the start and end of each line in the CSV file, and the "," string is used to delimit fields within each line. When I try to read this into numpy via: import numpy as np data = np.genfromtxt(csvfile, dtype=None, delimiter=',', names=True) all the data gets read in as string values, surrounded by double-quote characters. Not unreasonable, but not much use to me as I then have to go back and convert every column to its correct type When I use delimiter='","' instead, everything works as I'd like, except for the 1st and last fields. As the start of line and end of line characters are a single double-quote character, this isn't seen as a valid delimiter for the 1st and last fields, so they get read in as e.g. "04/13/2010 14:45:07.008 and 6.552373" - note the leading and trailing double-quote characters respectively. Because of these redundant characters, numpy assumes the 1st and last fields are both String types; I don't want that to be the case Is there a way of instructing numpy to read in files formatted in this fashion as I'd like, without having to go back and "fix" the structure of the numpy array after the initial read?

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• Retrieve 2 last posts for each category.

  - by Savageman

  Hello, Lets say I have 2 tables: blog_posts and categories. Each blog post belongs to only ONE category, so there is basically a foreign key between the 2 tables here. I would like to retrieve the 2 lasts posts from each category, is it possible to achieve this in a single request? GROUP BY would group everything and leave me with only one row in each category. But I want 2 of them. It would be easy to perform 1 + N query (N = number of category). First retrieve the categories. And then retrieve 2 posts from each category. I believe it would also be quite easy to perform M queries (M = number of posts I want from each category). First query selects the first post for each category (with a group by). Second query retrieves the second post for each category. etc. I'm just wondering if someone has a better solution for this. I don't really mind doing 1+N queries for that, but for curiosity and general SQL knowledge, it would be appreciated! Thanks in advance to whom can help me with this.

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• What are the best open-source software non-profits for making financial contributions and/or facilitating useful work?

  - by Jason S

  I'm not a great programmer myself (my main job is more electrical engineering) and have never really helped out with any open source projects, but I've benefited greatly from free and/or open-source software (MySQL, OpenOffice, Firefox, Apache, PHP, Java, etc.) and at some point would like to make some modest financial contributions to help keep this stuff going. I'm wondering, what are the best non-profits to make financial contributions? I'm aware of: Open Source Initiative (founded 10 years ago by several prominent figures including programmer and "The Cathedral and the Bazaar" author Eric S. Raymond) Free Software Foundation Mozilla Foundation Apache Foundation Anyone have a particular favorite? Ideally I'd like to give money to a non-profit that would foster some of the smaller but promising open-source and/or free software projects. The big projects like Firefox and Apache are already well-established. There are a few small individual shareware programs I've already paid for directly. But it's those middle-ground projects that I would really like my contributions to support. (one that comes to mind is a good GUI for Subversion or Mercurial.) It's one thing for a single person to donate a little $$ to a small project. It's another for a foundation or something to give larger grants to projects that give a good bang for the buck. Conservation organizations like The Nature Conservancy, or the Trust for Public Lands, have really honed this approach, but I'm not really sure if there's an equivalent model in software-land.

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• How do you word wrap a RichTextField for Blackberry

  - by Kai

  I've been trying to modify a rich text field to display correctly in its half of the horizontal field. The goal is this: --------------------------- | address is | ***********| | very long | ** IMAGE **| | state, zip | ***********| --------------------------- Where address is a single string separate from the city and zip. I am modifying the address field like this: RichTextField addrField = new RichTextField(address) { public int getPreferredWidth() { return 200; } protected void layout(int maxWidth,int maxHeight) { super.layout(getPreferredWidth(),maxHeight); setExtent(getPreferredWidth(), getHeight()); } }; The results look like this: ----------------------------- | address is ve| ***********| | state, zip | ** IMAGE **| | | ***********| ----------------------------- where clearly the address is just going under the image. Both horizontal fields are static 200 pixels wide. It's not like the system wouldn't know where to wrap the address. However, I have heard it is not easy to do this and is not done automatically. I have had no success finding a direct answer online. I have found people saying you need to do it in a custom layout manager, some refer to the RichTextField API, which is of no use. But nobody actually mentions how to do it. I understand that I may need to read character by character and set where the line breaks should happen. What I don't know is how exactly to do any of this. You can't just count characters and assume each is worth 5 pixels, and you shouldn't have to. Surely there must be some way to achieve this in a way that makes sense. Any suggestions?

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• Writing to a log4net FileAppender with multiple threads performance problems

  - by Wayne

  TickZoom is a very high performance app which uses it's own parallelization library and multiple O/S threads for smooth utilization of multi-core computers. The app hits a bottleneck where users need to write information to a LogAppender from separate O/S threads. The FileAppender uses the MinimalLock feature so that each thread can lock and write to the file and then release it for the next thread to write. If MinimalLock gets disabled, log4net reports errors about the file being already locked by another process (thread). A better way for log4net to do this would be to have a single thread that takes care of writing to the FileAppender and any other threads simply add their messages to a queue. In that way, MinimalLock could be disabled to greatly improve performance of logging. Additionally, the application does a lot of CPU intensive work so it will also improve performance to use a separate thread for writing to the file so the CPU never waits on the I/O to complete. So the question is, does log4net already offer this feature? If so, how do you do enable threaded writing to a file? Is there another, more advanced appender, perhaps? If not, then since log4net is already wrapped in the platform, that makes it possible to implement a separate thread and queue for this purpose in the TickZoom code. Sincerely, Wayne

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• Mirth is Not Picking Up Updated JAR File?

  - by ashes999

  I have some Mirth code (javascript) that's consuming one of my Java classes (let's call it SimpleClass). It seems that Mirth is not picking up my changes to my class. SimpleClass used to look something like this: public class Simpleclass { public SimpleClass(String one) { // do something with one } } Now it looks like: public class Simpleclass { public SimpleClass(String one, String two) { // store one and two } public void Execute() { // do something with one and two } } When I try and call SimpleClass with two strings, I get the error "Java constructor for SimpleClass with arguments string, string not found." When I try to run Execute, I get an error similar to "TypeError: method Execute not found." Perplexingly, I can still call SimpleClass("one string") to call the one-string constructor (which is now nowhere to be seen in the code). To get my code to work, I build a JAR file using ant, and deploy it to \\lib\custom. I have tried: Copying the new JAR and restarting Mirth while it's live Copying the new JAR after stopping Mirth, then starting Mirth Looking for other copies of my JAR or Mirth installations (there are none) Unzipping and reverse-engineering the JAR (it has the two-constructor code) Hashing the JAR (it matches what I'm building in ant) Restarting my computer (hey, you never know) I'm at a loss. I'm not sure why I'm not seeing the latest code. My channel has very simple Javascript: var sp = new Packages.com.hs.channel.scarborough.ScarboroughParser("one", "two"); I know it's not a configuration error of any kind, since this used to work (and does still work, albeit with the old code -- single-parameter constructor).

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• Managing common components with Fossil CVS

  - by Larry Lustig

  I'm a Fossil (and CVS configuration novice) attempting to create and manage a set of distributed Fossil repositories for a Delphi project. I have the following directory tree: Projects Some Project Delphi Components LookupListView Some Client Some Project For Client Some Other Project For Client Source Code Project Resources Project Database I am setting up Fossil version control in order to version and share Projects\Some Client\Some Other Project For Client\Source Code, which contains Delphi 2010 source for a database project. This project makes use of Projects\Delphi Components\LookupListView which is a Delphi component. I need this code to be included in the versioning system for my project. I will, in theory, need to include it in other Fossil repositories in the future, as well. If I create my Fossil repository at the Source Code or Some Other Project For Client level, I cannot add any code above that level to my repository. What is the proper way to deal with this? The two solutions that occur to me are 1) Creating a separate repository for LookupListView and make sure that everyone who uses a repository for a project that references it "knows" that they must also get the current version of this project as well. This seems to defeat the purpose of being able to obtain a complete, current version of the project with a single checkout. The problem is magnified because there are other common component dependencies in this project. 2) Establishing my Fossil repository in the Projects directory, so I can check in files from various subfolders. This seems to me to involve an awful lot of extra path-typing when doing adds, and also to impose my directory structure (Some Client\Some Other Project For Client\Source) on the other users of the repository -- in this case, the actual client. Any suggestions appreciated.

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• Scrolling with two fingers with a UIScrollView

  - by Craig

  I have an app where my main view accepts both touchesBegan and touchesMoved, and therefore takes in single finger touches, and drags. I want to implement a UIScrollView, and I have it working, but it overrides the drags, and therefore my contentView never receives them. I'd like to implement a UIScrollview, where a two finger drag indicates a scroll, and a one finger drag event gets passed to my content view, so it performs normally. Do I need create my own subclass of UIScrollView? Here's my code from my appDelegate where I implement the UIScrollView. @implementation MusicGridAppDelegate @synthesize window; @synthesize viewController; @synthesize scrollView; - (void)applicationDidFinishLaunching:(UIApplication *)application { // Override point for customization after app launch //[application setStatusBarHidden:YES animated:NO]; //[window addSubview:viewController.view]; scrollView.contentSize = CGSizeMake(720, 480); scrollView.showsHorizontalScrollIndicator = YES; scrollView.showsVerticalScrollIndicator = YES; scrollView.delegate = self; [scrollView addSubview:viewController.view]; [window makeKeyAndVisible]; } - (void)dealloc { [viewController release]; [scrollView release]; [window release]; [super dealloc]; }

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• Can GWT image sprites using ImageBundle be made to work in IE7 and IE6?

  - by aem

  I'm trying to use a ClientBundle in my GWT application to make multiple images get sent as a single file. I declare the bundle like so: public interface MyResources extends ClientBundle { public static final MyResources INSTANCE = GWT.create(MyResources.class); @Source("icon1.png") ImageResource icon1(); @Source("icon2.png") ImageResource icon2(); } This works great in Firefox and IE8, but in IE7 (and earlier) the whole sprite shows up in place of one of my original images - that is, icon1 is next to icon2 next to icon3, and so on. In IE8's developer tools using IE8-as-IE7 mode or Compatibility View, I can see that it's showing an image with a file name like 26BEFD2399A92A5DDA54277BA550C75B.cache.png, which is what I'd expect. So is there any way to make GWT image sprites work in IE7 and lower? If not, is there any way to gracefully degrade so users of other browsers get the speedup of spriting and IE7 and IE6 users get something that looks right but is slower? Edit: The Client Bundle Developer's Guide has a discussion of using ClientBundle and @sprite, and says "Support for IE6 isn't feasible in this format, because structural changes to the DOM are necessary to implement a "windowing" effect. Once it's possible to distinguish ie6 and ie7 in user.agent, we could revisit support for ie6. In the current implementation, the ie6 code won't render correctly, although is a purely cosmetic issue." Is this what's going on in my case, and is there a way to work around it? Showing all the images is "purely a cosmetic issue", but it's a pretty severe one.

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• Embedded SQL in OO languages like Java

  - by Steve De Caux

  One of the things that annoys me working with SQL in OO languages is having to define SQL statements in strings. When I used to work on IBM mainframes, the languages used an SQL preprocessor to parse SQL statements out of the native code, so the statements could be written in cleartext SQL without the obfuscation of strings, for instance in Cobol there is a EXEC SQL .... END-EXEC syntax construct that allows pure SQL statements to be embedded in the Cobol code. <pure cobol code, including assignment of value to local variable HOSTVARIABLE> EXEC SQL SELECT COL_A, COL_B, COL_C INTO :COLA, :COLB, :COLC FROM TAB_A WHERE COL_D = :HOSTVARIABLE END_EXEC <more cobol code, variables COLA, COLB, COLC have been set> ...this makes the SQL statement really easy to read & check for errors. Between the EXEC SQL .... END-EXEC tokens there are no constraints on indentation, linebreaking etc., so you can format the SQL statement according to taste. Note that this example is for a single-row select, when a multiple-row resultset is expected, the coding is different (but still v. easy to read). So, taking Java as an example What made the "old COBOL" approach undesirable ? Not only SQL, but system calls could be made much more readable with that approach. Let's call it the embedded foreign language preprocessor approach. Would an embedded foreign language preprocessor for SQL be useful to implement ? Would you see a benefit in being able to write native SQL statements inside java code ? Edit I'm really asking if you think SQL in OO languages is a throwback, and if not then what could be done to make it better.

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• DDD and Client/Server apps

  - by Christophe Herreman

  I was wondering if any of you had successfully implemented DDD in a Client/Server app and would like to share some experiences. We are currently working on a smart client in Flex and a backend in Java. On the server we have a service layer exposed to the client that offers CRUD operations amongst some other service methods. I understand that in DDD these services should be repositories and services should be used to handle use cases that do not fit inside a repository. Right now, we mimic these services on the client behind an interface and inject implementations (Webservices, RMI, etc) via an IoC container. So some questions arise: should the server expose repositories to the client or do we need to have some sort of a facade (that is able to handle security for instance) should the client implement repositories (and DDD in general?) knowing that in the client, most of the logic is view related and real business logic lives on the server. All communication with the server happens asynchronously and we have a single threaded programming model on the client. how about mapping client to server objects and vice versa? We tried DTO's but reverted back to exposing the state of our objects and mapping directly to them. I know this is considered bad practice, but it saves us an incredible amount of time) In general I think a new generation of applications is coming with the growth of Flex, Silverlight, JavaFX and I'm curious how DDD fits into this.

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• How to make Stack.Pop threadsafe

  - by user260197

  I am using the BlockingQueue code posted in this question, but realized I needed to use a Stack instead of a Queue given how my program runs. I converted it to use a Stack and renamed the class as needed. For performance I removed locking in Push, since my producer code is single threaded. My problem is how can thread working on the (now) thread safe Stack know when it is empty. Even if I add another thread safe wrapper around Count that locks on the underlying collection like Push and Pop do, I still run into the race condition that access Count and then Pop are not atomic. Possible solutions as I see them (which is preferred and am I missing any that would work better?): Consumer threads catch the InvalidOperationException thrown by Pop(). Pop() return a nullptr when _stack-Count == 0, however C++-CLI does not have the default() operator ala C#. Pop() returns a boolean and uses an output parameter to return the popped element. Here is the code I am using right now: generic <typename T> public ref class ThreadSafeStack { public: ThreadSafeStack() { _stack = gcnew Collections::Generic::Stack<T>(); } public: void Push(T element) { _stack->Push(element); } T Pop(void) { System::Threading::Monitor::Enter(_stack); try { return _stack->Pop(); } finally { System::Threading::Monitor::Exit(_stack); } } public: property int Count { int get(void) { System::Threading::Monitor::Enter(_stack); try { return _stack->Count; } finally { System::Threading::Monitor::Exit(_stack); } } } private: Collections::Generic::Stack<T> ^_stack; };

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• Accessing frame info in gdb

  - by Maelstrom

  In gdb, is there a way to access the contents of info frame in a script? I'm debugging a problem somewhere between Apache, PHP, APC and my own code, and I have about a hundred cores to choose from. Following the instructions here http://bugs.php.net/bugs-generating-backtrace.php I end up with a stacktrace like: #0 0x0121a31a in do_bind_function (opline=0xa94dd750, function_table=0x9b9cf98, compile_time=0 '\0') at /usr/src/debug/php-5.2.7/Zend/zend_compile.c:2407 #1 0x0124bb2e in ZEND_DECLARE_FUNCTION_SPEC_HANDLER (execute_data=0xbfef7990) at /usr/src/debug/php-5.2.7/Zend/zend_vm_execute.h:498 #2 0x01249dfa in execute (op_array=0xb79d5d3c) at /usr/src/debug/php-5.2.7/Zend/zend_vm_execute.h:92 #3 0x01261e31 in ZEND_INCLUDE_OR_EVAL_SPEC_VAR_HANDLER (execute_data=0xbfef80d0) at /usr/src/debug/php-5.2.7/Zend/zend_vm_execute.h:7809 #4 0x01249dfa in execute (op_array=0xb79d55ec) at /usr/src/debug/php-5.2.7/Zend/zend_vm_execute.h:92 ... #26 0x09caa894 in ?? () #27 0x00000000 in ?? () The stack will always look similar, with function execute and ZEND_something interleaved several times. I need to go up to the last instance of execute (up 2 in this case) and print myVar. Obviously gdb knows the function names, but does it surface them in any user variables I could access? Typing frame 2 shows a one-line version, and info frame shows a single stackframe in detail. I want to do something like while ($current_frame.function_name != "execute") {up;} print myVar but I don't see how to do it strictly within gdb. Is there a variable / structure / special memory location / something that allows access to gdb's information on either the whole stack (like bt) or to the current stack frame (like info frame)?

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• Problem with copying local data onto HDFS on a Hadoop cluster using Amazon EC2/ S3.

  - by Deepak Konidena

  Hi, I have setup a Hadoop cluster containing 5 nodes on Amazon EC2. Now, when i login into the Master node and submit the following command bin/hadoop jar <program>.jar <arg1> <arg2> <path/to/input/file/on/S3> It throws the following errors (not at the same time.) The first error is thrown when i don't replace the slashes with '%2F' and the second is thrown when i replace them with '%2F': 1) Java.lang.IllegalArgumentException: Invalid hostname in URI S3://<ID>:<SECRETKEY>@<BUCKET>/<path-to-inputfile> 2) org.apache.hadoop.fs.S3.S3Exception: org.jets3t.service.S3ServiceException: S3 PUT failed for '/' XML Error Message: The request signature we calculated does not match the signature you provided. check your key and signing method. Note: 1)when i submitted jps to see what tasks were running on the Master, it just showed 1116 NameNode 1699 Jps 1180 JobTracker leaving DataNode and TaskTracker. 2)My Secret key contains two '/' (forward slashes). And i replace them with '%2F' in the S3 URI. PS: The program runs fine on EC2 when run on a single node. Its only when i launch a cluster, i run into issues related to copying data to/from S3 from/to HDFS. And, what does distcp do? Do i need to distribute the data even after i copy the data from S3 to HDFS?(I thought, HDFS took care of that internally) IF you could direct me to a link that explains running Map/reduce programs on a hadoop cluster using Amazon EC2/S3. That would be great. Regards, Deepak.

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• How do you efficiently implement a document similarity search system?

  - by Björn Lindqvist

  How do you implement a "similar items" system for items described by a set of tags? In my database, I have three tables, Article, ArticleTag and Tag. Each Article is related to a number of Tags via a many-to-many relationship. For each Article i want to find the five most similar articles to implement a "if you like this article you will like these too" system. I am familiar with Cosine similarity and using that algorithm works very well. But it is way to slow. For each article, I need to iterate over all articles, calculate the cosine similarity for the article pair and then select the five articles with the highest similarity rating. With 200k articles and 30k tags, it takes me half a minute to calculate the similar articles for a single article. So I need another algorithm that produces roughly as good results as cosine similarity but that can be run in realtime and which does not require me to iterate over the whole document corpus each time. Maybe someone can suggest an off-the-shelf solution for this? Most of the search engines I looked at does not enable document similarity searching.

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• Safari Extension Questions

  - by Rob Wilkerson

  I'm in the process of building my first Safari extension--a very simple one--but I've run into a couple of problems. The extension boils down to a single, injected script that attempts to bypass the native feed handler and redirect to an http:// URI. My issues so far are twofold: The "whitelist" isn't working the way I'd expect. Since all feeds are shown under the "feed://" protocol, I've tried to capture that in the whitelist as "feed://*/*" (with nothing in the blacklist), but I end up in a request loop that I can't understand. If I set blacklist values of "http://*/*" and "https://*/*", everything works as expected. I can't figure out how to access my settings from my injected script. The script creates a beforeload event handler, but can't access my settings using the safari.extension.settings path indicated in the documentation. I haven't found anything in Apple's documentation to indicate that settings shouldn't be available from my script. Since extensions are such a new feature, even Google returns limited relevant results and most of those are from the official documentation. What am I missing? Thanks.

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• What makes these two R data frames not identical?

  - by Matt Parker

  UPDATE: I remembered dput() about the time Sharpie mentioned it. It's probably the row names. Back in a moment with an answer. I have two small data frames, this_tx and last_tx. They are, in every way that I can tell, completely identical. this_tx == last_tx results in a frame of identical dimensions, all TRUE. this_tx %in% last_tx, two TRUEs. Inspected visually, clearly identical. But when I call identical(this_tx, last_tx) I get a FALSE. Hilariously, even identical(str(this_tx), str(last_tx)) will return a TRUE. If I set this_tx <- last_tx, I'll get a TRUE. What is going on? I don't have the deepest understanding of R's internal mechanics, but I can't find a single difference between the two data frames. If it's relevant, the two variables in the frames are both factors - same levels, same numeric coding for the levels, both just subsets of the same original data frame. Converting them to character vectors doesn't help. Background (because I wouldn't mind help on this, either): I have records of drug treatments given to patients. Each treatment record essentially specifies a person and a date. A second table has a record for each drug and dose given during a particular treatment (usually, a few drugs are given each treatment). I'm trying to identify contiguous periods during which the person was taking the same combinations of drugs at the same doses. The best plan I've come up with is to check the treatments chronologically. If the combination of drugs and doses for treatment[i] is identical to the combination at treatment[i-1], then treatment[i] is a part of the same phase as treatment[i-1]. Of course, if I can't compare drug/dose combinations, that's right out.

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• jQuery/Ajax with Zend Framework

  - by Nathan

  I've been tinkering around with Zend-Framework and Jquery for a month or so, and finally started tinkering with them together using ZendX_JQuery. It seems I've ran into something that at first seemed it should be simple, So maybe I'm just missing something here. I have a view along the lines of: $this->ajaxLink( $this->escape($var->title), $this->baseUrl() . "/another/action", array('update' => '#domain' . $var->id , 'complete' => '$("#domain' . $var->id .'").toggle("slow");')); echo '<div id="domain"' . $var->id . '" style="display:none;" ></div>'; Which works correctly, when the link displayed by the code above is clicked it loads the contents returned from /another/action into the domain"id" div. The problem occurs when the view loaded by the above contains an ajaxLink() the ajax link stops working. This can be fixed by adding an option to the ajaxLink() array "inline" = true but what if I need other JQuery views helpers to work when loaded into the page via ajax i.e. dialogContainer() I guess I could simply be asking how to control where zendx jquery helper puts java script. by default it is trying to put all statments in the <head> section in a single <script> tag. I need away around that for views displayed from an ajax call. Does Dojo try and force all php rendered javascript/ajax into the head also? Thanks.

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