In this article Barry Mavin, CEO and Chief Software Architect for Recital, gives details on Working with user-defined Functions in the Recital Database Server.
Overview
User-defined functions (UDFs) are collections of statements written in the Recital 4GL (compatible with Visual FoxPro) stored under a name and saved in a Database. User-defined functions are just-in-time compiled by the Recital database engine. User-defined functions can be used in SQL statements to extend the power and flexibility of the inbuilt functions. Using the Database Administrator in Recital Enterprise Studio, you can easily create, view, modify, and test Stored Procedures, Triggers, and user-defined functions.
Tip
You can also extend the Recital Database Server with C Extension Libraries and use the functions defined within that library also.Creating and Editing user-defined functions
To create a new User-defined function, right-click the Procedures node in the Databases tree of the Project Explorer and choose Create. To modify an existing User-defined function select the User-defined function in the Databases Tree in the Project Explorer by double-clicking on it or selecting Modify from the context menu. By convertion we recommend that you name your User-defined functions beginning with "f_xxx_", where xxx is the name of the table that they are associated with.
Testing the user-defined function
To test run the user-defined function, select it in the Databases Tree in the Project Explorer by double-clicking on it. Once the Database Administrator is displayed, click the Run button to run it.
Example
Example: user-defined function "f_order_details_total".
////////////////////////////////////////////////////////////////////////
// example user-defined function
function f_order_details_total(pUnitprice, pQuantity, pDiscount)
return (pUnitprice + pQuantity + pDiscount) > 0
endfunc
Example: using the user-defined function in a SQL SELECT statement.
//////////////////////////////////////////////////////////////////////// // sample code to use a user-defined function in a SQL SELECT statement select * from customers where f_order_details_total(Unitprice, Quantity, Discount)
Using user-defined function libraries with the Recital Database Server
You can place all of the user-defined functions associated with a particular table into a procedure library. You then define an Open Trigger for the table that opens up the procedure library whenever the table is accessed. This is a much faster way of using user-defined functions as it reduces the amount of file open/close operations during a query and also simplifies development and maintenance.
By convertion we recommend that you should name the library using the convention "lib_xxx", where xxx is the name of the table that the library is associated with.
Example: procedure library in lib_order_details.
////////////////////////////////////////////////////////////////////////
// example user-defined functions
function f_order_details_total(pUnitprice, pQuantity, pDiscount)
return (pUnitprice * pQuantity - pDiscount) > 0
endfunc
function f_order_details_diff(pUnitprice, pQuantity, pDiscount, pValue)
return f_order_details_total(pUnitprice, pQuantity, pDiscount) - pValue
endfunc
Example: Open Trigger in dt_order_details_open.
//////////////////////////////////////////////////////////////////////// // This trigger will open up the procedure library when the table is opened set procedure to lib_order_details additive
Example: Close Trigger in dt_order_details_close.
//////////////////////////////////////////////////////////////////////// // This trigger will close the procedure library when the table is closed close procedure lib_order_details
Example: using the user-defined function in a SQL SELECT statement.
//////////////////////////////////////////////////////////////////////// // sample code to use a user-defined function in a SQL SELECT statement select * from customers where f_order_details_total(Unitprice, Quantity, Discount)
User-defined functions can also be used with any of the Client Drivers that work with the Recital Database Server.
The getUIComponentBitmapData method can create bitmapdata for a given IUIComponent. Pass any UIcomponent to get its respective bitmapdata.
public static function getUIComponentBitmapData(target:IUIComponent):BitmapData {
var resultBitmapData:BitmapData = new BitmapData(target.width, target.height);
var m:Matrix = new Matrix();
resultBitmapData.draw(target, m);
return resultBitmapData;
}
Now convert the bitmapdata to a jpeg bytearray.
private static function encodeToJPEG(data:BitmapData, quality:Number = 75):ByteArray {
var encoder:JPGEncoder = new JPGEncoder(quality);
return encoder.encode(data);
}
Now encode the ByteArray into Base64.
public static function base64Encode(data:ByteArray):String {
var encoder:Base64Encoder = new Base64Encoder();
encoder.encodeBytes(data);
return encoder.flush();
}
Upload the base64 encoded ByteArray to the server.
public static uploadData():void {
var url:String = "saveFile.php";
var urlRequest:URLRequest = new URLRequest(url);
urlRequest.method = URLRequestMethod.POST;
var urlLoader:URLLoader = new URLLoader();
var urlVariables:URLVariables = new URLVariables();
urlVariables.file = jpgEncodedFile; // as returned from base64Encode()
urlLoader.data = urlVariables;
urlLoader.load(urlRequest);
}
The saveFile.php file on the server.
On exit of an .rsp page.
SAVE DATASESSION TO m_state
_SESSION["state"] = m_state
On entry to an .rsp page.
IF type( _session["state"] ) != "U"
m_state = _session["state"]
RESTORE DATASESSION FROM m_state
ENDIF
We are pleased to announce the release of Recital 10.0.3.
Here is a brief list of features and functionality that you will find in the 10.0.3 release.
- New Commands:
- SET TMPNAMPATH ON|OFF
- REMOVE TABLE - New Functions:
- CURSORGETPROP()
- CURSORSETPROP()
- CURVAL()
- GETFLDSTATE()
- OLDVAL()
- TABLEREVERT()
- TABLEUPDATE()
- SETFLDSTATE() - Enhanced Functions:
- TMPNAM() - additional parameter to specify the return of basename only
- MAILATTACH() - parameter changed from array to filename to allow directory and file extension to be specified - Enhancements:
- DO level increased from 32 to 64. - Fixes:
- Delay exiting Recital after SYS(3) or SYS(2015)
- SET SOFTSEEK issue when search key above first record in index
- Compilation error with REPLACE command after UDF call
- FETCH INTO memvars error
- END TRANSACTION at command prompt error
- ROLLBACK locking error
- Linux ODBC Driver undefined symbol error
- RELEASE variable with same name as variable in calling program issue
- SQLCODE() issue on non-gateway data access
- Issuing two SQLEXEC() calls error
- LASTSEQNO() in workareas > 1 error
- SET RELATION to detail table in workarea 1 issue
- LIST STATUS on empty table delay
- SET AUTOCATALOG alias entries error
- ADD OBJECT in DEFINE CLASS error
- DEACTIVATE WINDOW error
- SORT error
- Other reported bugs
In this article Barry Mavin explains step by step how to setup a Linux HA (High Availability) cluster for the running of Recital applications on Redhat/Centos 5.3 although the general configuration should work for other linux versions with a few minor changes.
This guide will assist you in setting up an rsnapshot backup server on your network. rsnapshot uses rsync via ssh to perform unattended backups of multiple systems in your network. The guide can be found on the centos website here.
Some options of hdparm are dangerous and are generally listed as such in the man page.
Hdparm is available from SourceForge and there is even a version for Windows.
In Adobe's own words:"Adobe® AIR® is a cross-operating system runtime that lets developers combine HTML, Ajax, Adobe Flash®, and Adobe Flex® technologies to deploy rich Internet applications (RIAs) on the desktop."
The outcome of this combination of technologies is that developers can design and render quite beautiful user interfaces cross platform. For us desktop Linux users it is nice to have
an additional avenue for obtaining and running attractive desktop applications.Examples of great Adobe air applications are Adobe.com for My Desktop, TweetDeck and the Times Reader. You can download these applications and many more at the Adobe Marketplace.
The easiest way to install Adobe Air on Fedora 12 is to download the latest build from Adobe, click here.
Once you have downloaded the .bin file do the following at the shell:
su - chmod +x AdobeAIRInstaller.bin ./AdobeAIRInstaller.binOnce you have Air installed, there is a slight tweak you will have to do to get it running on Fedora 12, it is related to the security certificates. This can be remedied in one simple line at the shell prompt as root.
su - for c in /etc/opt/Adobe/certificates/crypt/*.0; do aucm -n $(basename $c) -t true; doneWhat this line is doing is using the aucm which is the Adobe Unix certificate manager to set the certificates installed as trusted.
You will now be able to go to the Adobe Marketplace and download and run Air applications without any issues.
Enjoy!
We are pleased to announce the release of Recital 10.0.2.
Here is a brief list of features and functionality that you will find in the 10.0.2 release.
- New commands
SAVE/RESTORE DATASESSION [TO variable]
CONNECT "connectString"
DISCONNECT - New functions (OData compatible)
startsWith(haystack as character, needle as character)
endsWith(haystack as character, needle as character)
indexOf(haystack as character, needle as character)
substringOf(haystack as character, needle as character)
concat(expC1, expC2) - New system variables
_LASTINSERTEDSYNCNUM - Enhanced commands
Added CONNSTRING "connectingString" to the USE command to connect to remote servers (Recital, MySQL, PostgreSQL, Oracle, ODBC) - Further SQL query optimizer improvements to boost performance
- Performance improvements in Recital Web
- Forced all temporary files into temp directory (improves performance when local tmpfs is used as temp directory and reduces network i/o)
- Fixed cookie and session variable problems in Recital Web
- Fixed problem with temporary files being left after some server queries involving memos and object data types
- Improved performance of the Windows ODBC driver
- Fixed a security flaw in Recital Web
- Fixed all reported bugs