I've written a C# netcoreapp 3.1 webapi app that tries to read a Teiid VDB table via Npgsql.EntityFrameworkCore.PostgreSQL 3.1.0.
Whenever my app reads any data like this:
_context.Campaigns.ToList();
the following error occurs:
NotSupportedException: The deprecated floating-point date/time format is not supported by Npgsql.
Googling it I've found this: Npgsql: Old floating point representation for timestamps not supported . Unfortunately, the Npgsql.EntityFrameworkCore.PostgreSQL project stopped supporting the deprecated floating-point date/time format of PostgreSQL but Teiid seems to be still using it.
I've also tried the old version 2.2.4 of Npgsql.EntityFrameworkCore.PostgreSQL with a .net Core 2 app that didn't have this problem but failed to read and write double values from/to Teiid.
AFAIK, the only working way to access Teiid data from .net Core apps is via System.Data.ODBC.
Is there any configuration or tweak on Teiid to make its PostgreSQL emulation using the new integer date/time format?
Or if not, is there any plan to update the Teiid PostgreSQL emulation?
Or if not, is there any plan to update the Teiid PostgreSQL emulation?
I don't think the full context is quite captured here. The current state of the pg emulation is that it supports the binary format only for bytea, integral, float, double, and date types. The driver should be sending time/timestamp in text format.
If additional binary format type support is needed, that would require an enhancement.
As for what binary format to support, we need to match the expectation for the pg version that we are emulating, which is currently 8.2. If there is a connection / session variable to control the expected format we could look to support that.
The last efforts to support npgsql were two years ago, so it's likely that their driver is now doing things that we didn't expect. So you should log an enhancement about supporting the latest and greatest version, which could coordinate any of the subtasks.
I am looking at developing a simple case management system, a sort of ticketing system where users can enter data in forms, moving from one form to another pressing Next, Next etc.
The information will then be stored in a database, and kept on a case by case basis, will be available for searching and modifications later.
I was thinking about the Microsoft Access Developer toolkit but it seems it is no longer supported and the latest version is 2007.
Can someone suggest some form of tool that I could use please?
Thanks, Noel
It really depends what kind of language knowledge you have and for what platform you are targeting (fat client for windows, Linux etc or web)
There are tons of application development tools
But if would like something similar to access you can give Libreoffice Base a try.
I got several build errors on my very new Codename One application:
The build complains on the FileNotfoundException class and the String split() method. Any idea why ?
xxx\Page.java:11: error: cannot find symbol
import java.io.FileNotFoundException;
symbol: class FileNotFoundException
location: package java.io
and
xxx\Page.java:97: error: cannot find symbol
final String[] parts = number_label.split("-");
symbol: method split(String)
location: variable number_label of type String
By the way, is that true that there is a restriction to use java 1.5 in CodenameOne ? I couldn't find where to say to compile with java 7.
Kind regards,
EDIT: This reply is somewhat out of date. Codename One supports a subset of Java 8 now although string.split() is still a problematic API call.
Codename One supports a subset of Java 5, you shouldn't try and change that since the server translation code relies on bytecode behaviors of the target Java 5 and only supports a very specific subset of the API.
The reasoning is simple, since Codename One has multiple VM implementations (iOS, Dalvik/ART, XMLVM/ParparVM, blackberry etc.) its really hard to test new stuff (e.g. newer bytecodes) and its really hard to add new API's in a way that will be totally cross platform. You can use StringUtils.split() to implement this functionality as well as StringTokenizer.
Limiting the API's also allows us to keep the executable efficient and small (relatively). Compared to a more full featured VM we are at least 5 times smaller in production. This is a big deal for mobile apps...
We are working on consolidating the various VM's on the server side which will allow us to add core VM API's more easily in the future as well as features like Java 8 support.
You can learn more in this answer:
How does Codename One work?
I'm creating a web platform destined to the customers of a certain company. The company requires that the platform allows the streaming of videos.
It's important to note that the company will be the one to add the videos to the platform, dinamically, from a software built by me for that purpose, and each video will be referenced on a sql server table.
I've never done streaming before so I'm asking 2 things:
The first is about some guidance in silverlight streaming(tutorials, articles, examples, etc)
The other is my main concern. I have a few video samples from the company, and all of them are over 200 MBytes and can go up to 2GB, so I know I have to re-encode them to become smaller. But, how do I do this... I mean, do I have to re-enconde them, manually, one at a time, or is there a way to do it automatically as a new video is added?
I have Expression Studio Encoder 4 pro, but never really used it, and as far as I can tell, I have to manually add each video to do the enconding. Again... is there a way to do this dinamically??
Thanks
Not all video formats and encodings are supported by Silverlight. See this page for a list of supported formats. You will probably need to recompress your videos not only to reduce their size but also to normalize the format.
The recompression could be done in a windows service running in the background, the more appropriated libraries to be used will probably depend on the target format you will use. For wmv files I would recommend using Windows Media Format SDK,the (currently deprecated) Windows Media Encoder SDK or its succesor Expression Studio Encoder SDK. For using H264 as target I would recommend using ffmepg.
You should decide on a delivery protocol depending on the number of users you can forsee for your website. HTTP might not be the best choice, since there are other protocols like RTTP, usually more suitable for video streaming.
I cannot access ANY database by ANY means from within Delphi XE Professional. What I mean by accessing the data base is:
having the live database appear via
components in the Object Inspector,
when the connected property is set
to true
using the Data Explorer to create
and explore database connections
EDIT:
SORTED !!
The core problem is that communication into the database, including specifically the communication generated by the IDE and any code built using the drivers was problematic.
Confounding and masking sub-issues were:
Missing or misplaced DLLs.
The Data Explorer does not fully support dbExpress drivers.
There is a bug within the 2009 IDE code, found by Chee-Yang Chau when writing the dbxFirebird driver, which limits static linking of drivers into Delphi. It is not known if this bug extends to 2010 or XE.
When using the Object Inspector, it is easy to cause the IDE to revert changed connection parameters to their default values.
Some drivers had incorrect default values (eg assuming the client dll was always gdb32.dll irrespective of whether the database was Interbase or Firebird).
Installation of two versions of Interbase led to some clashes in database communication - server names generated by the tools were odd; and the view of the databases depended on which installation of the Interbase tools were used.
The documentation available is of varying dates; refers to different versions; and as a result often appears contradictory.
END EDIT:
Approaches tried:
Multiple databases
Multiple different drivers/components
Accessing the database through other external tools, such as IBSQL and Flame Robin.
Raising questions (here and here) on SO.
Raising questions on the support forums for Firebird, Embarcardo, and Flame Robin.
Environment:
OS: Windows 7 Ultimate 64bit:
Delphi Embarcadero® RAD Studio XE Professional Version 15.0.3953.35171
Database: W1-V2.5.0.26074 Firebird 2.5 (64 bit)
Connection technology: dbExpress
Delphi Professional does not support Firebird with the native dbExpress drivers that come with Delphi. You need the Enterprise or Architect version of Delphi in order for the native firebird dbExpress driver to work.
I have Delphi 2010 Professional. I didn't want to spend the extra money on the E or A version and I failed to read the feature matrix to see that the Firebird dbExpress driver is not available with the Pro version.
I have found a few really nice videos that show how to connect to Firebird using Delphi. However, when I tried to follow along with my Professonal version nothing worked.
Shame on me and more shame on Embarcadero for touting that Delphi supports Firebird in big bold print but not mentioning that you need the Enterprise or Architect version except in the tiny fine print.
I can now write code to access Firebird within the IDE. I have (limited, but sufficient) access to the drivers within the IDE. Specifically, the drivers appear in the Data Explorer, which can be used to generate default values for the SQLConnection (dbExpress component). These can be accessed and used within the Object Inspector. The workaround to the IDE bug quoted below is necessary to ensure the communication parameters are correct. When writing database code, it is necessary to compile in the source for the dbExpress driver.
The following code is the minimum, with minimum parameter set, necessary to establish and test a database connection:
unit Unit2;
interface
uses Classes, SqlExpr, Dialogs, dbxDevartInterbase;
var SQLConnection1 : TSQLConnection;
implementation
{$R *.dfm}
begin
SQLConnection1 := TSQLConnection.Create(nil);
with SQLConnection1 do
begin
ConnectionName := 'TestConnection';
DriverName := 'DevartInterBase';
LibraryName := 'dbexpida40.dll';
VendorLib := 'fbclient.dll';
GetDriverFunc := 'getSQLDriverInterBase';
Params.Clear;
Params.Add('User_Name=SYSDBA');
Params.Add('Password=masterkey');
Params.Add('Database=localhost:C:\Program Files\Firebird\Firebird_2_5\examples\empbuild\employee.fdb');
Open;
If Connected then ShowMessage('Connection is active');
Free;
end;
end.
The workaround, courtesy of Bob Swart on one of the Codegear forums is:
The trick is to select a
ConnectionName value, which will then
assign a value to the Driver property
and all other properties like
LibraryName, VendorLib and
GetDriverFunc.
Then, make changes - if needed - to
the subproperties of the Driver
property, and finally clear the name
of the Driver property.
This will leave all your changes in
the Params list (which you can also
manually edit if you wish).
Note: leave the ConnectionName set -
if you clear that one, the parameters
will be cleared again.
Now you can compile your application
and deploy it without the need for
dbxdrivers.exe or dbxconnections.ini
(but you need to deploy the DLLs
specified in the LibraryName and
VendorLib, of course).
Also make sure to set LoginPrompt to
False and leave LoadParamsOnConnect
set to False, too.
BOUNTY AWARD
I have awarded the bounty to this answer as it was the one that pointed me away from investigation of the IDE, its installation and configuration, to investigation of the connection into the database.
END
DK about Firebird 64 bit - -no experience. But I've always had a lot of trouble with dbExpress. Never any problem with the included IB components suite. But there is a lot of confusion with IB versions...
But IMO you're best served using the ADO ('DBGo') components as opposed to any proprietary IB or Delphi specific drivers. What you need is an ADO provider for IB, available #:
http://www.ibprovider.com/eng/ - and as others have said, avoid using localhost, use 127.0.0.1, or better still, determine the true IP address of your workstation (ping machine-name...) And are you sure you don't have some kind of firewall or intrustion protection that may be involved?
You also need to make sure that your IB connection is configured properly - local or TCP, and no, don't use quotation marks for your names, pwrds, etc. The error message you got seems to indicate that you're trying to connect via TCP and it's not properly configured. What happened between the time it worked and the time it didn't work? Shut down Delphi? Reboot the machine? Explain please....
No 'special permissions' are needed - you simply need to ensure that your database server and client are properly installed and configured. In terms of functionality you can do everything with the pro version - just that the drivers etc aren't included in the package.
Again, IMO go for ADO and you'll never look back.
HTH,
MNG
Have you tried Paradox via the Borland Database Engine (BDE) and related components: TTable TQuery TStoredProc TDatabase and TSession?
If memory serves me correctly, at least as far back as Delphi 3, the distinguishing factor between "professional" and the "higher-level" editions has been the type of database development "out the box".
In Delphi 1, the BDE was the only way to do out-the-box database development.
Delphi 2 permitted a custom database layer by abstracting parts of the database component hierarchy.
Delphi 3 Professional provided BDE and drivers for file-based databases and Interbase.
One level up (Enterprise?*) they provided BDE drivers for typical client-server database access: SQL Server, Sybase, Interbase, Oracle,... (and native drivers for Interbase)
Another level up (Architect?*) introduced multi-tier development with Midas. Unfortunately, Borland took a step back with Midas, because the multi-tier components were again hard-wired to the BDE. (This was resolved in Delphi 4.)
?* Please note, I may be mistaken about the exact naming of these editions. Around about that time I formed the opinion that Borland was merely coming up with "grander" names in order to charge more for features that didn't really offer as much benefit as the 'big-cheque-writing-CIOs' came to believe - leaving developers to deal with the fallout. (Yes, I have battle-scars from Midas I.)
Rant aside, the theory was....
If one embarked on entry-level database development, you would purchase Delphi ?? Professional. Develop your system against a file-based database or Interbase via the BDE.
If you later needed to scale-up: you would upgrade Delphi, purchase your chosen SQL RDBMS, switch your connectivity via the TDatabase component, and apply the few necessary tweaks.
NOTE: In Delphi 3, you could switch to Native Interbase (personally not recommended) or use third-party components for non-Midas development. From Delphi 4 up, ADO and DevExpress started receiving more attention and nowdays, the BDE seems to be pretty much forgotten.
Of course theory & practice seldom frequent the same pubs. However, with a few cautionary pointers, you should be able to develop a significant file based solution that can be upgraded relatively painlessly.
Keep your business logic out of the database. This is quite possibly the biggest and most frequently encountered error. Huge chunks of systems are often written in triggers and stored procedures, making it more difficult to maintain or migrate a system.
Avoid platform-specific database techniques. This should go without saying, but if you don't explicitly look out for them, you will encounter problems.
Particularly relevant to file based database systems, many support special locking mechanisms - avoid them! They don't scale well to large multi-user systems in any case.
Generating of artificial keys often varies by platform: Generators, IDENTITY columns, how you get the new value.
Plan your system for large volumes of data. Identify the high-transaction tables, and avoid using uncontrolled retrieval of all records. I'd also avoid the TTable in this situation - BDE does a lot of interesting background things with TTable, and behaviour can vary according to driver and platform.
Disclaimer: All this was a long time ago, so some of the details may be a bit sketchy.
Disclaimer2: I don't have any experience with Delphi XE specifically. I currently use D5 professionally, and D2009 in my personal capacity.