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  • Is it possible to programmatically set the state of the shift and control keys?

    - by Stephen Harrison
    The reason I am asking is that I am thinking of building a foot switch to act as shift and control keys - well two switches, one for each foot. I'm planning on using the Arduino for this and writing a small C# application to detect when the switch has been pressed that would then set the state of shift or control. I would rather not have to write a keyboard driver for the Arduino as I would like it to do other things as well.

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  • List of Django model instance foreign keys losing consistency during state changes.

    - by Joshua
    I have model, Match, with two foreign keys: class Match(model.Model): winner = models.ForeignKey(Player) loser = models.ForeignKey(Player) When I loop over Match I find that each model instance uses a unique object for the foreign key. This ends up biting me because it introduces inconsistency, here is an example: >>> def print_elo(match_list): ... for match in match_list: ... print match.winner.id, match.winner.elo ... print match.loser.id, match.loser.elo ... >>> print_elo(teacher_match_list) 4 1192.0000000000 2 1192.0000000000 5 1208.0000000000 2 1192.0000000000 5 1208.0000000000 4 1192.0000000000 >>> teacher_match_list[0].winner.elo = 3000 >>> print_elo(teacher_match_list) 4 3000 # Object 4 2 1192.0000000000 5 1208.0000000000 2 1192.0000000000 5 1208.0000000000 4 1192.0000000000 # Object 4 >>> I solved this problem like so: def unify_refrences(match_list): """Makes each unique refrence to a model instance non-unique. In cases where multiple model instances are being used django creates a new object for each model instance, even if it that means creating the same instance twice. If one of these objects has its state changed any other object refrencing the same model instance will not be updated. This method ensure that state changes are seen. It makes sure that variables which hold objects pointing to the same model all hold the same object. Visually this means that a list of [var1, var2] whose internals look like so: var1 --> object1 --> model1 var2 --> object2 --> model1 Will result in the internals being changed so that: var1 --> object1 --> model1 var2 ------^ """ match_dict = {} for match in match_list: try: match.winner = match_dict[match.winner.id] except KeyError: match_dict[match.winner.id] = match.winner try: match.loser = match_dict[match.loser.id] except KeyError: match_dict[match.loser.id] = match.loser My question: Is there a way to solve the problem more elegantly through the use of QuerySets without needing to call save at any point? If not, I'd like to make the solution more generic: how can you get a list of the foreign keys on a model instance or do you have a better generic solution to my problem? Please correct me if you think I don't understand why this is happening.

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  • How long do FireFox, Chrome, Safari, and Opera cache SSL/TLS session keys?

    - by MJ
    To try to use a reason SSL/TLS session key timeout on the server-side, I'd like to know how long popular browsers cache session keys on the client. Microsoft describes this information for Windows/IE here: http://technet.microsoft.com/en-us/library/cc776467(WS.10).aspx But, I haven't been able to find similar information for other popular browsers. Does anyone know? Thanks!

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  • Berkeley DB: btree prefix comparison for directory-like keys?

    - by Mark Harrison
    I'm going to index a BDB with keys that look a lot like directory paths ('/foo/bar', '/foo/baz', etc, with levels of slashes generally < 10). Does anybody have any experience with using a Btree prefix comparison routine[1] for this? Are the savings worthwhile? Any references to experience papers on this subject? [1] http://www.stanford.edu/class/cs276a/projects/docs/berkeleydb/ref/am_conf/bt_prefix.html

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  • Swing's KeyListener and multiple keys pressed at the same time.

    - by Negai
    Hi everyone, is there any conventional way in swing of tracking down the events, when two keyboard keys are pressed at the same time? I have a couple of ideas e.g. remembering the key and event generation time so that we could in a consecutive event handler invocation check the time difference between these two events and decide, whether it's a two-button event or not. Phew. But it looks like a kludge. Thanks in advance.

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  • how to create a system-wide independent universal counter object primarily for Database keys?

    - by andora
    I would like to create/use a system-wide independent universal 'counter object' that can be called via COM in a thread-safe manner. The counter object will be passed an ID to identify which counter to return, handle the counting, 'persist' the count (occasionally), have reasonable performance (as fast as possible) perhaps capable of 1000 counts per second or better (1mS) and be accessible cross-process/out-of-process. The current count status must be persisted between object restarts/shutdowns. The counter object is liklely to be a 'singleton' type object implemented in some form of free-threaded dictionary, containing maybe 10 counters (perhaps 50 max). The count needs to be monotonic and consistent, (ie: guaranteed unique sequential values). Each counter should have a few methods, like reset, inc, dec, set, clear, remove. As a luxury, I would like to have a variable-increment (ie: 'step by' value). To support thread-safefty, perhaps some sorm of critical-section or mutex call. It just needs to return a long/4byte signed integer. I really want something that can be called from anywhere, including VBScript, so I figure COM is my preferred solution. The primary use of this is for database keys. I am unable to use autoinc or guid type keys and have ruled out database-generated counting systems at this point. I've spent days researching this and I have really struggled to find a solution. The best I can find is a free-threaded dictionary object that can be instantiated using COM+ from Motobit - it seems to offer all the 'basics' and I guess I could create some form of wrapper for this. So, here are my questions: Does such a 'general purpose counter-object already exist? Can you direct me to it? (MS did do an IIS/ASP object called 'MSWC.Counter' but this isn't 'cross-process'/ out-of-process component and isn't thread-safe. (but if it was, it would do!) What is the best way of creating such a Component? (I'd prefer VB6 right-now, [don't ask!] but can do in VB.NET2005 if I had to). I don't have the skills/knowledge/tools to use anything else. I am desparate for a workable solution. I need specific guidance! If anybody can code something up for me I am prepared to pay for it.

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  • What do I need to distribute (keys, certs) for Python w/ SSL-socket connection?

    - by fandingo
    I'm trying to write a generic server-client application that will be able to exchange data amongst servers. I've read over quite a few OpenSSL documents, and I have successfully setup my own CA and created a cert (and private key) for testing purposes. I'm stuck with Python 2.3, so I can't use the standard "ssl" library. Instead, I'm stuck with PyOpenSSL, which doesn't seem bad, but there aren't many documents out there about it. My question isn't really about getting it working. I'm more confused about the certificates and where they need to go. Here are my two programs that do work: Server: #!/bin/env python from OpenSSL import SSL import socket import pickle def verify_cb(conn, cert, errnum, depth, ok): print('Got cert: %s' % cert.get_subject()) return ok ctx = SSL.Context(SSL.TLSv1_METHOD) ctx.set_verify(SSL.VERIFY_PEER|SSL.VERIFY_FAIL_IF_NO_PEER_CERT, verify_cb) # ?????? ctx.use_privatekey_file('./Dmgr-key.pem') ctx.use_certificate_file('Dmgr-cert.pem') # ?????? ctx.load_verify_locations('./CAcert.pem') server = SSL.Connection(ctx, socket.socket(socket.AF_INET, socket.SOCK_STREAM)) server.bind(('', 50000)) server.listen(3) a, b = server.accept() c = a.recv(1024) print(c) Client: from OpenSSL import SSL import socket import pickle def verify_cb(conn, cert, errnum, depth, ok): print('Got cert: %s' % cert.get_subject()) return ok ctx = SSL.Context(SSL.TLSv1_METHOD) ctx.set_verify(SSL.VERIFY_PEER, verify_cb) # ?????????? ctx.use_privatekey_file('/home/justin/code/work/CA/private/Dmgr-key.pem') ctx.use_certificate_file('/home/justin/code/work/CA/Dmgr-cert.pem') # ????????? ctx.load_verify_locations('/home/justin/code/work/CA/CAcert.pem') sock = SSL.Connection(ctx, socket.socket(socket.AF_INET, socket.SOCK_STREAM)) sock.connect(('10.0.0.3', 50000)) a = Tester(2, 2) b = pickle.dumps(a) sock.send("Hello, world") sock.flush() sock.send(b) sock.shutdown() sock.close() I found this information from ftp://ftp.pbone.net/mirror/ftp.pld-linux.org/dists/2.0/PLD/i586/PLD/RPMS/python-pyOpenSSL-examples-0.6-2.i586.rpm which contains some example scripts. As you might gather, I don't fully understand the sections between the " # ????????." I don't get why the certificate and private key are needed on both the client and server. I'm not sure where each should go, but shouldn't I only need to distribute one part of the key (probably the public part)? It undermines the purpose of having asymmetric keys if you still need both on each server, right? I tried alternating removing either the pkey or cert on either box, and I get the following error no matter which I remove: OpenSSL.SSL.Error: [('SSL routines', 'SSL3_READ_BYTES', 'sslv3 alert handshake failure'), ('SSL routines', 'SSL3_WRITE_BYTES', 'ssl handshake failure')] Could someone explain if this is the expected behavior for SSL. Do I really need to distribute the private key and public cert to all my clients? I'm trying to avoid any huge security problems, and leaking private keys would tend to be a big one... Thanks for the help!

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  • Performance of String literals vs constants for Session[...] dictionary keys

    - by FreshCode
    Session[Constant] vs Session["String Literal"] Performance I'm retrieving user-specific data like ViewData["CartItems"] = Session["CartItems"]; with a string literal for keys on every request. Should I be using constants for this? If yes, how should I go about implementing frequently used string literals and will it significantly affect performance on a high-traffic site? Related question does not address ASP.NET MVC or Session.

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  • How do you check the presence of many keys in a Python dictinary?

    - by Thierry Lam
    I have the following dictionary: sites = { 'stackoverflow': 1, 'superuser': 2, 'meta': 3, 'serverfault': 4, 'mathoverflow': 5 } To check if there are more than one key available in the above dictionary, I will do something like: 'stackoverflow' in sites and 'serverfault' in sites The above is maintainable with only 2 key lookups. Is there a better way to handle checking a large number of keys in a very big dictionary?

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  • Clojure: I have many sorted maps and want to reduce in order all there values a super maps of keys -> vector

    - by Alex Foreman
    I have seen this but can't work out how to apply it (no pun intended) to my situation. I have a sorted list of maps like this: (note there can be more than two keys in the map) ({name1 3, name2 7}, {name1 35, name2 7}, {name1 0, name2 3}) What I am after is this data structure afterwards: ({:name1 [3,35,0]}, {:name2 [7,7,3]}) Ive been struggling with this for a while and cant seem to get anywhere near. Caveats: The data must stay sorted and I have N keywords not just two.

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  • Network bandwidth bottleneck for sorting of mapreduce intermediate keys?

    - by Zubair
    I have been learning the mapreduce algorithm and how it can potentially scale to millions of machines, but I don't understand how the sorting of the intermediate keys after the map phase can scale, as there will be: 1,000,000 x 1,000,000 : potential machines communicating small key / value pairs of the intermediate results with each other? Isn't this a bottleneck?

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  • Add SQL Azure database to Azure Web Role and persist data with entity framework code first.

    - by MagnusKarlsson
    In my last post I went for a warts n all approach to set up a web role on Azure. In this post I’ll describe how to add an SQL Azure database to the project. This will be described with an as minimal as possible amount of code and screen dumps. All questions are welcome in the comments area. Please don’t email since questions answered in the comments field is made available to other visitors. As an example we will add a comments section to the site we used in the previous post (Länk här). Steps: 1. Create a Comments entity and then use Scaffolding to set up controller and view, and add ConnectionString to web.config. 2. Create SQL Azure database in Management Portal and link the new database 3. Test it online!   1. Right click Models folder, choose add, choose “class…” . Name the Class Comment. 1.1 Replace the Code in the class with the following: using System.Data.Entity; namespace MvcWebRole1.Models { public class Comment {    public int CommentId { get; set; }    public string Name { get; set; }      public string Content { get; set; } } public class CommentsDb : DbContext { public DbSet<Comment> CommentEntries { get; set; } } } Now Entity Framework can create a database and a table named Comment. Build your project to assert there are no build errors.   1.2 Right click Controllers folder, choose add, choose “class…” . Name the Class CommentController and fill out the values as in the example below.     1.3 Click Add. Visual Studio now creates default View for CRUD operations and a Controller adhering to these and opens them. 1.3 Open Web.config and add the following connectionstring in <connectionStrings> node. <add name="CommentsDb” connectionString="data source=(LocalDB)\v11.0;Integrated Security=SSPI;AttachDbFileName=|DataDirectory|\CommentsDb.mdf;Initial Catalog=CommentsDb;MultipleActiveResultSets=True" providerName="System.Data.SqlClient" />   1.4 Save All and press F5 to start the application. 1.5 Go to http://127.0.0.1:81/Comments which will redirect you through CommentsController to the Index View which looks like this:     Click Create new. In the Create-view, add name and content and press Create.   1: // 2: // POST: /Comments/Create 3:  4: [HttpPost] 5: public ActionResult Create(Comment comment) 6: { 7: if (ModelState.IsValid) 8: { 9: db.CommentEntries.Add(comment); 10: db.SaveChanges(); 11: return RedirectToAction("Index"); 12: } 13:  14: return View(comment); 15: } 16:    The default View() is Index so that is the View you will come to. Looking like this: 1: // 2: // GET: /Comments/ 3: 4: public ActionResult Index() 5: { 6: return View(db.CommentEntries.ToList()); 7: } Resulting in the following screen dump(success!):   2. Now, go to the Management portal and Create a new db.   2.1 With the new database created. Click the DB icon in the left most menu. Then click the newly created database. Click DASHBOARD in the top menu. Finally click Connections strings in the right menu to get the connection string we need to add in our web.debug.config file.   2.2 Now, take a copy of the connection String earlier added to the web.config and paste in web.debug.conifg in the connectionstrings node. Replace everything within “ “ in the copied connectionstring with that you got from SQL Azure. You will have something like this:   2.3 Rebuild the application, right click the cloud project and choose “Package…” (if you haven’t set up publishing profile which we will do in our next blog post). Remember to choose the right config file, use debug for staging and release for production so your databases won’t collide. You should see something like this:   2.4 Go to Management Portal and click the Web Services menu, choose your service and click update in the bottom menu.   2.5 Link the newly created database to your application. Click the LINKED RESOURCES in the top menu and then click “Link” in the bottom menu. You should get something like this. 3. Alright then. Under the Dashboard you can find the link to your application. Click it to open it in a browser and then go to ~/Comments to try it out just the way we did locally. Success and end of this story!

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  • Data model for timesheet to task and/or timesheet to project?

    - by John
    Let's say I want to make a simple project tracking system. A manager can create a project. Then he can create tasks for that project. Team members can record the hours they work for each task or for the project as a whole. Is the following design for the t_timesheet table a good idea? timesheet_id - primary key, autoincrement project_id - not null, foreign key constraint to t_project task_id - nullable, foreign key constraint to t_task user_id - not null, foreign key constraint to t_user hours - decimal Or should I do something like this: timesheet_id - primary key, autoincrement task_id - not null, foreign key constraint to t_task user_id - not null, foreign key constraint to t_user hours - decimal In the second option, I intend to always have a record in t_task labelled "miscellaneous items" with a foreign key to the relevant t_project record. Then I'll be able to track all hours for a project that aren't for any particular task. Are any of the ideas above good? What would be better?

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  • BizTalk Cross Reference Data Management Strategy

    - by charlie.mott
    Article Source: http://geekswithblogs.net/charliemott This article describes an approach to the management of cross reference data for BizTalk.  Some articles about the BizTalk Cross Referencing features can be found here: http://home.comcast.net/~sdwoodgate/xrefseed.zip http://geekswithblogs.net/michaelstephenson/archive/2006/12/24/101995.aspx http://geekswithblogs.net/charliemott/archive/2009/04/20/value-vs.id-cross-referencing-in-biztalk.aspx Options Current options to managing this data include: Maintaining xml files in the format that can be used by the out-of-the-box BTSXRefImport.exe utility. Use of user interfaces that have been developed to manage this data: BizTalk Cross Referencing Tool XRef XML Creation Tool However, there are the following issues with the above options: The 'BizTalk Cross Referencing Tool' requires a separate database to manage.  The 'XRef XML Creation' tool has no means of persisting the data settings. The 'BizTalk Cross Referencing tool' generates integers in the common id field. I prefer to use a string (e.g. acme.country.uk). This is more readable. (see naming conventions below). Both UI tools continue to use BTSXRefImport.exe.  This utility replaces all xref data. This can be a problem in continuous integration environments that support multiple clients or BizTalk target instances.  If you upload the data for one client it would destroy the data for another client.  Yet in TFS where builds run concurrently, this would break unit tests. Alternative Approach In response to these issues, I instead use simple SQL scripts to directly populate the BizTalkMgmtDb xref tables combined with a data namepacing strategy to isolate client data. Naming Conventions All data keys use namespace prefixing.  The pattern will be <companyName>.<data Type>.  The naming conventions will be to use lower casing for all items.  The data must follow this pattern to isolate it from other company cross-reference data.  The table below shows some sample data. (Note: this data uses the 'ID' cross-reference tables.  the same principles apply for the 'value' cross-referencing tables). Table.Field Description Sample Data xref_AppType.appType Application Types acme.erp acme.portal acme.assetmanagement xref_AppInstance.appInstance Application Instances (each will have a corresponding application type). acme.dynamics.ax acme.dynamics.crm acme.sharepoint acme.maximo xref_IDXRef.idXRef Holds the cross reference data types. acme.taxcode acme.country xref_IDXRefData.CommonID Holds each cross reference type value used by the canonical schemas. acme.vatcode.exmpt acme.vatcode.std acme.country.usa acme.country.uk xref_IDXRefData.AppID This holds the value for each application instance and each xref type. GBP USD SQL Scripts The data to be stored in the BizTalkMgmtDb xref tables will be managed by SQL scripts stored in a database project in the visual studio solution. File(s) Description Build.cmd A sqlcmd script to deploy data by running the SQL scripts below.  (This can be run as part of the MSBuild process).   acme.purgexref.sql SQL script to clear acme.* data from the xref tables.  As such, this will not impact data for any other company. acme.applicationInstances.sql   SQL script to insert application type and application instance data.   acme.vatcode.sql acme.country.sql etc ...  There will be a separate SQL script to insert each cross-reference data type and application specific values for these types.

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