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Search found 24 results on 1 pages for 'heinzi'.

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• Does it make sense to use ORM in Android development?

  - by Heinzi

  Does it make sense to use an ORM in Android development or is the framework optimized for a tighter coupling between the UI and the DB layer? Background: I've just started with Android development, and my first instinct (coming from a .net background) was to look for a small object-relational mapper and other tools that help reduce boilerplate clode (e.g. POJOs + OrmLite + Lombok). However, while developing my first toy application I stumbled upon a UI class that explicitly requires a database cursor: AlphabetIndexer. That made me wonder if maybe the Android library is not suited for a strict decoupling of UI and DB layer and that I will miss out on a lot of useful, time-saving features if I try to use POJOs everywhere (instead of direct database access). Clarification: I'm quite aware of the advantages of using ORM in general, I'm specifically interested in how well the Android class library plays along with it.

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• What's Microsoft's strategy on Windows CE development?

  - by Heinzi

  Lots of specialized mobile devices use Windows CE or Windows Mobile. I'm not talking about smart phones here -- I know that Windows Phone 7 is Microsoft's current technology of choice here. I'm talking about barcode readers, embedded devices, industry PDAs with specialized hardware, etc... the kind of devices (Example 1, Example 2) where Windows Phone Silverlight development is not an option (no P/Invoke to access the hardware, etc.). Since direct Compact Framework support has been dropped in Visual Studio 2010, the only option to develop for these device currently is to use outdated development tools (VS 2008), which already start to cause trouble on modern machines (e.g. there's no supported way to make the Windows Mobile Device Emulator's network stack work on Windows 7). Thus, my question is: What are Microsoft's plans regarding these mobile devices? Will they allow native applications on Windows Phone, such that, for example, barcode reader drivers can be developed that can be accessed in Silverlight applications? Will they re-add "native" Compact Framework support to Visual Studio and just haven't found the time yet? Or will they leave this niche market?

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• Is there an established convention for separating Windows file names in a string?

  - by Heinzi

  I have a function which needs to output a string containing a list of file paths. I can choose the separation character but I cannot change the data type (e.g. I cannot return a List<string> or something like that). Wanting to use some well-established convention, my first intuition was to use the semicolon, similar to what Windows's PATH and Java's CLASSPATH (on Windows) environment variables do: C:\somedir\somefile.txt;C:\someotherdir\someotherfile.txt However, I was surprised to notice that ; is a valid character in an NTFS file name. So, is the established best practice to just ignore this fact (i.e. "no sane person should use ; in a file name and if they do, it's their own fault") or is there some other established character for separating Windows paths or files? (The pipe (|) might be a good choice, but I have not seen it used anywhere yet for this purpose.)

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• How do you keep code with continuations/callbacks readable?

  - by Heinzi

  Summary: Are there some well-established best-practice patterns that I can follow to keep my code readable in spite of using asynchronous code and callbacks? I'm using a JavaScript library that does a lot of stuff asynchronously and heavily relies on callbacks. It seems that writing a simple "load A, load B, ..." method becomes quite complicated and hard to follow using this pattern. Let me give a (contrived) example. Let's say I want to load a bunch of images (asynchronously) from a remote web server. In C#/async, I'd write something like this: disableStartButton(); foreach (myData in myRepository) { var result = await LoadImageAsync("http://my/server/GetImage?" + myData.Id); if (result.Success) { myData.Image = result.Data; } else { write("error loading Image " + myData.Id); return; } } write("success"); enableStartButton(); The code layout follows the "flow of events": First, the start button is disabled, then the images are loaded (await ensures that the UI stays responsive) and then the start button is enabled again. In JavaScript, using callbacks, I came up with this: disableStartButton(); var count = myRepository.length; function loadImage(i) { if (i >= count) { write("success"); enableStartButton(); return; } myData = myRepository[i]; LoadImageAsync("http://my/server/GetImage?" + myData.Id, function(success, data) { if (success) { myData.Image = data; } else { write("error loading image " + myData.Id); return; } loadImage(i+1); } ); } loadImage(0); I think the drawbacks are obvious: I had to rework the loop into a recursive call, the code that's supposed to be executed in the end is somewhere in the middle of the function, the code starting the download (loadImage(0)) is at the very bottom, and it's generally much harder to read and follow. It's ugly and I don't like it. I'm sure that I'm not the first one to encounter this problem, so my question is: Are there some well-established best-practice patterns that I can follow to keep my code readable in spite of using asynchronous code and callbacks?

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• In retrospect, has it been a good idea to use three-valued logic for SQL NULL comparisons?

  - by Heinzi

  In SQL, NULL means "unknown value". Thus, every comparison with NULL yields NULL (unknown) rather than TRUE or FALSE. From a conceptional point of view, this three-valued logic makes sense. From a practical point of view, every learner of SQL has, one time or another, made the classic WHERE myField = NULL mistake or learned the hard way that NOT IN does not do what one would expect when NULL values are present. It is my impression (please correct me if I am wrong) that the cases where this three-valued logic helps (e.g. WHERE myField IS NOT NULL AND myField <> 2 can be shortened to WHERE myField <> 2) are rare and, in those cases, people tend to use the longer version anyway for clarity, just like you would add a comment when using a clever, non-obvious hack. Is there some obvious advantage that I am missing? Or is there a general consensus among the development community that this has been a mistake?

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• Configuration data: single-row table vs. name-value-pair table

  - by Heinzi

  Let's say you write an application that can be configured by the user. For storing this "configuration data" into a database, two patterns are commonly used. The single-row table CompanyName | StartFullScreen | RefreshSeconds | ... ---------------+-------------------+------------------+-------- ACME Inc. | true | 20 | ... The name-value-pair table ConfigOption | Value -----------------+------------- CompanyName | ACME Inc. StartFullScreen | true (or 1, or Y, ...) RefreshSeconds | 20 ... | ... I've seen both options in the wild, and both have obvious advantages and disadvantages, for example: The single-row tables limits the number of configuration options you can have (since the number of columns in a row is usually limited). Every additional configuration option requires a DB schema change. In a name-value-pair table everything is "stringly typed" (you have to encode/decode your Boolean/Date/etc. parameters). (many more) Is there some consensus within the development community about which option is preferable?

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• Pattern for a class that does only one thing

  - by Heinzi

  Let's say I have a procedure that does stuff: void doStuff(initalParams) { ... } Now I discover that "doing stuff" is quite a compex operation. The procedure becomes large, I split it up into multiple smaller procedures and soon I realize that having some kind of state would be useful while doing stuff, so that I need to pass less parameters between the small procedures. So, I factor it out into its own class: class StuffDoer { private someInternalState; public Start(initalParams) { ... } // some private helper procedures here ... } And then I call it like this: new StuffDoer().Start(initialParams); or like this: new StuffDoer(initialParams).Start(); And this is what feels wrong. When using the .NET or Java API, I always never call new SomeApiClass().Start(...);, which makes me suspect that I'm doing it wrong. Sure, I could make StuffDoer's constructor private and add a static helper method: public static DoStuff(initalParams) { new StuffDoer().Start(initialParams); } But then I'd have a class whose external interface consists of only one static method, which also feels weird. Hence my question: Is there a well-established pattern for this type of classes that have only one entry point and have no "externally recognizable" state, i.e., instance state is only required during execution of that one entry point?

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• Postfix: LDAP not working (warning: dict_ldap_lookup: Search base not found: 32: No such object)

  - by Heinzi

  I set up LDAP access with postfix. ldapsearch -D "cn=postfix,ou=users,ou=system,[domain]" -w postfix -b "ou=users,ou=people,[domain]" -s sub "(&(objectclass=inetOrgPerson)(mail=[mailaddr]))" delivers the correct entry. The LDAP config file looks like root@server2:/etc/postfix/ldap# cat mailbox_maps.cf server_host = localhost search_base = ou=users,ou=people,[domain] scope = sub bind = yes bind_dn = cn=postfix,ou=users,ou=system,[domain] bind_pw = postfix query_filter = (&(objectclass=inetOrgPerson)(mail=%s)) result_attribute = uid debug_level = 2 The bind_dn and bind_pw should be the same as I used above with ldapsearch. Nevertheless, calling postmap doesn't work: root@server2:/etc/postfix/ldap# postmap -q [mailaddr] ldap:/etc/postfix/ldap/mailbox_maps.cf postmap: warning: dict_ldap_lookup: /etc/postfix/ldap/mailbox_maps.cf: Search base 'ou=users,ou=people,[domain]' not found: 32: No such object If I change LDAP configuration, so that anonymous users have complete access to LDAP olcAccess: {-1}to * by * read then it works: root@server2:/etc/postfix/ldap# postmap -q [mailaddr] ldap:/etc/postfix/ldap/mailbox_maps.cf [user-id] But when I restrict this access to the postfix user: olcAccess: {-1}to * by dn="cn=postfix,ou=users,ou=system,[domain]" read by * break it doesn't work but produces the error printed above (although ldapsearch works, only postmap doesn't). Why doesn't it work when binding with a postfix DN? I think I set up the LDAP ACL for the postfix user correctly, as the ldapsearch command should prove. What can be the reason for this behaviour?

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• Does SQL Server Maintainance Cleanup consider exact times when deleting old backups?

  - by Heinzi

  Let's say I have a daily maintainance task that: Backups all databases and then removes backups that are older than 3 days. Now let's say the first backup at day 1, starting at 10:00, results in the following files db1.bak 2012-01-01 10:04 db2.bak 2012-01-01 10:06 Now let's say at day 4 the first step of the maintainance task (backup the DBs) happens to finish at 10:05. Will SQL Server delete db1.bak and keep db2.bak (would be logical, but might be surprising for the user) or keep both or remove both?

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• Windows 7: Computer does not enter automatic standby

  - by heinzi

  My Windows 7 PC is set to automatically enter standby ("sleep mode") after 30 minutes. For some reason it stopped working a few days ago (it keeps on running). Is there some systematic way to determine what is preventing the system from automatically entering sleep mode after the designated idle time? Manually sending the machine to sleep works fine. The monitor also enters power save mode automatically, so the "idling detection" of Windows seems to work fine.

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• How to safely remove a device blocked by the System process with a handle on \$Extend\$RmMetadata\$Txf

  - by Heinzi

  I have an external HDD which I would like to "safely remove". Unfortunately, my system (Windows 7 x64) complains that "the device is currently in use". Using Process Explorer I discovered which process is holding a handle on the device: Obviously, System is not a process that I can just kill and be done with it. I've done a bit of research and this seems to be a common problem, but no solution has been found so far (except for rebooting the machine, which I'd like to avoid if possible). Is there any solution to this problem that I've missed?

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• Under which circumstances can a *local* user account access a remote SQL Server with a trusted connection?

  - by Heinzi

  One of our customers has the following configuration: On the domain controller, there's an SQL Server. On his PC (WinXP), he logs on with LocalPC\LocalUser. In Windows Explorer, he opens DomainController\SomeShare and authenticates as Domain\Administrator. He starts our application, which opens a trusted connection (Windows authentication) to the SQL Server. It works. In SSMS, the connection shows up with the user Domain\Administrator. Firstly, I was surprised that this even works. (My first suspicion was that there is a user with the same name and password in the domain, but there is no user LocalUser in the domain.) Then we tried to reproduce the same behaviour on his new PC, but failed: On his new PC (Win7), he logs on with OtherLocalPC\OtherLocalUser. In Windows Explorer, he opens DomainController\SomeShare and authenticates as Domain\Administrator. He starts our application, which opens a trusted connection (Windows authentication) to the SQL Server. It fails with the error message Login failed for user ''. The user is not associated with a trusted SQL Server connection. Hence my question: Under which conditions can a non-domain user access a remote SQL Server using Windows Authentication with different credentials? Apparently, it's possible (it works on his old PC), but why? And how can I reproduce it?

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• warning BC40056: Namespace or type specified in the Imports 'MS.Internal.Xaml.Builtins' doesn't cont

  - by Heinzi

  I have a WPF VB.NET project in Visual Studio 2008. For some reason, Visual Studio thinks that it needs to add an Imports MS.Internal.Xaml.Builtins to every auto-generated XAML partial class (= the nameOfXamlFile.g.vb files), resulting in the following warning: warning BC40056: Namespace or type specified in the Imports 'MS.Internal.Xaml.Builtins' doesn't contain any public member or cannot be found. Make sure the namespace or the type is defined and contains at least one public member. Make sure the imported element name doesn't use any aliases. I can remove the Imports line, but, since this is an auto-generated file, it reappears every time that the project is rebuilt. This warning message is annoying and clutters my error list. Is ther something that can be done about it? Or is it a known bug?

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• Free lightweight XML text editor to include with an application

  - by Heinzi

  Our application uses a XML configuation file. I thought that it would be nice to distribute some small, lightweight XML editor with our application that the user can use to edit the config file. Features should be: Small and lightweight (ideally, a small .exe that does not require installation), free, with license terms that permit distributing it with a commercial application, understands XML schemas (auto-completion, show validation errors). Does anyone know of such an editor?

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• IIS 7.5, ASP.NET, impersonation, and access to C:\Windows\Temp

  - by Heinzi

  Summary: One of our web applications requires write access to C:\Windows\Temp. However, no matter how much I weaken the NTFS permission, procmon shows ACCESS DENIED. Background (which might or might not be relevant for the problem): We are using OLEDB to access an MS Access database (which is located outside of C:\Windows\Temp). Unfortunately, this OLEDB driver requires write access to the user profile's TEMP directory (which happens to be C:\Windows\Temp when running under IIS 7.5), otherwise the dreaded "Unspecified Error" OleDbException is thrown. See KB 926939 for details. I followed the steps in the KB article, but it doesn't help. Details: This is the output of icacls C:\Windows\Temp. For debugging purposes I gave full permissions to Everyone. C:\Windows\Temp NT AUTHORITY\SYSTEM:(OI)(CI)(F) CREATOR OWNER:(OI)(CI)(IO)(F) BUILTIN\IIS_IUSRS:(OI)(CI)(S,RD) BUILTIN\Users:(CI)(S,WD,AD,X) BUILTIN\Administrators:(OI)(CI)(F) Everyone:(OI)(CI)(F) However, this is the screenshot of procmon: Desired Access: Generic Read/Write, Delete Disposition: Create Options: Synchronous IO Non-Alert, Non-Directory File, Random Access, Delete On Close, Open No Recall Attributes: NT ShareMode: None AllocationSize: 0 Impersonating: MYDOMAIN\myuser

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• XML: What to use as a list separator

  - by Heinzi

  There are two ways to specify lists of values in XML. Variant 1: <Database Name="myDatabase"> <Table Name="myTable1" /> <Table Name="myTable2" /> <Table Name="myTable3" /> ... </Database> Variant 2: <Database Name="myDatabase" Tables="myTable1 myTable2 myTable3 ..." /> Clearly, Variant 1 is cleaner and can be extended more easily, but im many cases Variant 2 is more readable and "user-friendly". When using Variant 2, what should be used as the separator? The XML Schema standard seems to prefer whitespace, whereas some real-world examples use commas instead. Is there a particular reason to choose one over the other (assuming that the values contain neither whitspace nor commas)?

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• Why do ASP.NET applications appear to be running in a terminal server session?

  - by Heinzi

  Running the following ASPX page (IIS 6, Server 2003 R2) <%@ Page Language="vb" AutoEventWireup="false" %> <% Response.Write("Am I running in a terminal server session: " & _ System.Windows.Forms.SystemInformation.TerminalServerSession) %> yields the following output: Am I running in a terminal server session: True Why? IIS is running as a service, not as a Terminal Services application... (BTW, according to Reflector, SystemInformation.TerminalServerSession is just a wrapper for GetSystemMetrics(SM_REMOTESESSION).)

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• The woes of (sometimes) storing "date only" in datetimes

  - by Heinzi

  We have two fields from and to (of type datetime), where the user can store the begin time and the end time of a business trip, e.g.: From: 2010-04-14 09:00 To: 2010-04-16 16:30 So, the duration of the trip is 2 days and 7.5 hours. Often, the exact times are not known in advance, so the user enters the dates without a time: From: 2010-04-14 To: 2010-04-16 Internally, this is stored as 2010-04-14 00:00 and 2010-04-16 00:00, since that's what most modern class libraries (e.g. .net) and databases (e.g. SQL Server) do when you store a "date only" in a datetime structure. Usually, this makes perfect sense. However, when entering 2010-04-16 as the to date, the user clearly did not mean 2010-04-16 00:00. Instead, the user meant 2010-04-16 24:00, i.e., calculating the duration of the trip should output 3 days, not 2 days. I can think of a few (more or less ugly) workarounds for this problem (add "23:59" in the UI layer of the to field if the user did not enter a time component; add a special "dates are full days" Boolean field; store "2010-04-17 00:00" in the DB but display "2010-04-16 24:00" to the user if the time component is "00:00"; ...), all having advantages and disadvantages. Since I assume that this is a fairly common problem, I was wondering: Is there a "standard" best-practice way of solving it? If there isn't, have you experienced a similar requirement, how did you solve it and what were the pros/cons of that solution?

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• DateTime: Require the user to enter a time component

  - by Heinzi

  Checking if a user input is a valid date or a valid "date + time" is easy: .NET provides DateTime.TryParse (and, in addition, VB.NET provides IsDate). Now, I want to check if the user entered a date including a time component. So, when using a German locale, 31.12.2010 00:00 should be OK, but 31.12.2010 shouldn't. I know I could use DateTime.TryParseExact like this: Dim formats() As String = {"d.M.yyyy H:mm:ss", "dd.M.yyyy H:mm:ss", _ "d.MM.yyyy H:mm:ss", "d.MM.yyyy H:mm:ss", _ "d.M.yyyy H:mm", ...} Dim result = DateTime.TryParseExact(userInput, formats, _ Globalization.CultureInfo.CurrentCulture, ..., result) but then I would hard-code the German format of specifying dates (day dot month dot year), which is considered bad practice and will make trouble should we ever want to localize our application. In addition, formats would be quite a large list of all possible combinations (one digit, two digits, ...). Is there a more elegant solution?

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• Windows CE 5.0 emulator needed

  - by Heinzi

  I need an emulator for Windows CE 5.0 to test an embedded device (not PDA or smartphone) application that I am developing. This is what I have already tried: Visual Studio 2008 Pro includes an emulator. Unfortunately, it does not include a Windows CE image (only Windows Mobile and Smartphone). Yes, there is a difference, see the screenshots here. Windows CE includes a "start button", windows that can be minimized, moved around etc. There is a Windows CE Device Emulator available from Microsoft. Apart from the fact that its license only permits non-commercial use, it does not run in Windows 7 (it requires .net Framework 1.1, which is incompatible with Windows 7) nor in Windows XP mode (error message: "Emulator for Windows CE will not run one virtual machine within another. Please run the virtual machine on the host operating system"). Is there any option that I have missed?

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• WPF: Aligning the base line of a Label and its TextBox

  - by Heinzi

  Let's say I have a simple TextBox next to a Label: <StackPanel> <StackPanel Orientation="Horizontal"> <Label Margin="3">MyLabel</Label> <TextBox Margin="3" Width="100">MyText</TextBox> </StackPanel> ... </StackPanel> This yields the following result: As you can see, the base lines of MyLabel and MyText are not aligned, which looks ugly. Of course, I could start playing around with the margins until they match up, but since this is such a common requirement I'm sure that WPF provides a much easier and more elegant solution, which I just haven't found yet...

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• Vanilla WPF application hangs on one customer's machine

  - by Heinzi

  At a customer, one of our WPF applications started to hang. When trying to reproduce the problem with a minimal working example, I discovered that even the most basic (non-trivial) WPF application will hang on that machine. Example A: Create a new C# WPF project in Visual Studio 2008. Change nothing, compile it and run it on the customer's machine. It will run. Example B: Take Example A, and add a TextBlock to the main form Window1: <Window ...> <Grid> <TextBlock>Test</TextBlock> </Grid> </Window> Compile the application and run it on the customer's machine. It will hang: The title bar and the window border is visible, the inside is transparent and the window does not react to anything (cannot be moved or closed). The application must be shut down using the task manager. Obviously, this customer's WPF is broken. Is this a known issue, i.e., has anyone encountered it before and already knows how to solve it (e.g. reinstall .net 3.5 SP1, etc.)? The development machine is W7SP1, the customer's machine is XP (probably SP3, didn't check).

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• ASP.NET: convert UNC to file:/// URL

  - by Heinzi

  I need to convert UNC paths to file:/// URLs, e.g. \\fileserver\share\dir\some file.ext --> file://///fileserver/share/dir/some%20file.ext Is there some built-in function for this?

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• Make sure <a href="local file"> is opened outside of browser

  - by Heinzi

  For an Intranet web application (document management), I want to show a list of files associated with a certain customer. The resulting HTML is like this: <a href="file:///server/share/dir/somefile.docx">somefile.docx</a> <a href="file:///server/share/dir/someotherfile.pdf">somefile.pdf</a> <a href="file:///server/share/dir/yetanotherfile.txt">yetanotherfile.txt</a> This works fine. Unfortunetly, when clicking on a text file (or image file), Internet Explorer (and I guess most other browsers as well) insist on showing it in the browser instead of opening the file with the associated application (e.g. Notepad). In our case, this is undesired behavior, since it does not allow the user to edit the file. Is there some workaround to this behavior (e.g. something like <a href="file:///..." open="external">)? I'm aware that this is a browser-specific thing, and an IE-only solution would be fine (it's an Intranet application after all).

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