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In this article Barry Mavin, CEO and Chief Software Architect for Recital, details how to use the Recital Database Server with Visual FoxPro. 

 

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When debugging C code it is common to write debugging to an external text file using the __FILE__ and __LINE__ preprocessor defines to trace execution flow.

Unfortunately java does not support __FILE__ and __LINE__ but you can get the same functionality with this code which can be placed in one of your libraries.
	
public static void showTrace(String msg)
{
	if (msg.length() > 0) System.out.println(msg);
	System.out.println("Trace: " + 
				   "file " + new Throwable().getStackTrace()[1].getFileName() +
				   " class " + new Throwable().getStackTrace()[1].getClassName() +
				   " method " + new Throwable().getStackTrace()[1].getMethodName() +
				   " line " + new Throwable().getStackTrace()[1].getLineNumber());
}
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Recital 10.0.0 Linux x86 is now available

The full download for linux x86 can be downloaded from here.

Release notes can be found here.

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A good article describing the configuration of samba for file/record locking can be found here.

Basically you must add these directives to the smb.conf file:

[data] 
oplocks = False 
level2 oplocks = False

The default oplock type is Level1. Level2 oplocks are enabled on a per-share basis in the smb.conf file. Alternately, you could disable oplocks on a per-file basis within the share: 

veto oplock files = /*.dbf/*.DBF/*.ndx/*.NDX/*.dbx/*.DBX/*.dbt/*.DBT/

You can further tune samba by following this guide.

If you specify the Common Internet File System (CIFS) when you mount the samba share then you must specify the following options
mount -t cifs {mount-point} -o username=name,pass=pass,directio
The directio option is used to not do inode data caching on files opened on this mount. This precludes mmaping files on this mount. In some cases with fast networks and little or no caching benefits on the client (e.g. when the application is doing large sequential reads bigger than page size without rereading the same data) this can provide better performance than the default behavior which caches reads (readahead) and writes (writebehind) through the local Linux client pagecache if oplock (caching token) is granted and held. Note that direct allows write operations larger than page size to be sent to the server.

If you get the following error when trying to mount the {mount-point}
Apr 22 16:57:39 bailey kernel: Status code returned 0xc000006d NT_STATUS_LOGON_FAILURE
Apr 22 16:57:39 bailey kernel:  CIFS VFS: Send error in SessSetup = -13
Apr 22 16:57:39 bailey kernel:  CIFS VFS: cifs_mount failed w/return code = -13
The you need to create the Samba user specified on the mount command
smbpasswd -a username
FYI - Make sure you umount all the Samba {mount-point(s)} before shutting down Samba.
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This link provides a decent covering of this topic.
http://www.the-art-of-web.com/css/border-radius/
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In this article Barry Mavin, CEO and Chief Software Architect for Recital, details how to work with Triggers in the Recital Database Server.

Overview

A trigger is a special kind of stored procedure that runs when you modify data in a specified table using one or more of the data modification operations: UPDATE, INSERT, or DELETE.

Triggers can query other tables and can include complex SQL statements. They are primarily useful for enforcing complex business rules or requirements. For example, you can control whether to allow a new order to be inserted based on a customer's current account status.

Triggers are also useful for enforcing referential and data integrity.

Triggers can be used with any data source that is handled natively by the Recital Database Engine. This includes Recital, FoxPro, FoxBASE, Clipper, dBase, CISAM, and RMS data,

Creating and Editing Triggers

To create a new Trigger,  right-click the Procedures node in the Databases tree of the Project Explorer and choose Create. To modify an existing Trigger select the Trigger in the Databases Tree in the Project Explorer by double-clicking on it, or select Modify from the context menu. By convertion we recommend that you name your Stored Procedures beginning with "sp_xxx_", user-defined functions with "f_xxx_", and Triggers with "dt_xxx_", where xxx is the name of the table that they are associated with.

Associating Triggers with a Table

Once you have written your Triggers as detailed above you can associate them with the operations performed on a Table by selecting the Table tab.

The Tables tab allows you to select a Trigger procedure by clicking on the small button at the right of the Text field.

Types of Triggers

As can be seen from the Tables tab detailed below, The Recital Database Server handles 6 distinct types of Triggers.

Open Trigger

The Open Trigger is called after is a table is opened but before any operations are performed on it. You can use this trigger to record a log of table usage or provide a programmable means of checing security. If the Trigger procedure returns .F. (false), then the table is not opened. You can use a TRY...CATCH block around the associated command to inform the user.

Close Trigger

The Close Trigger is called just prior to a table being closed. In this trigger you may find it useful to get transaction counts by using the IOSTATS() built-in 4GL function, and record these values in a transaction log.

Update Trigger

The Update Trigger is called prior to a record update operation being performed. You can use this trigger to perform complex application or data specific validation. If the Trigger procedure returns .F. (false), then the record is not updated. You can use inform the user from within the Trigger procedure the reason that the data cannot be updated.

Delete Trigger

The Delete Trigger is called prior to a record delete operation being performed. You can use this trigger to perform complex application or data specific validation such as cross-table lookups e.g. attempting to delete a customer recortd when there are still open orders for that specific customer. If the Trigger procedure returns .F. (false), then the record is not deleted.

Insert Trigger

The Insert Trigger is called prior to a record insert (append) operation being performed. You can use this trigger to perform such tasks as setting up default values of columns within the record. If the Trigger procedure returns .F. (false), then the record is not inserted.

Rollback Trigger

The RollbackTrigger is called prior to a rollback operation being performed from within a form. If the Trigger procedure returns .F. (false), then the record is not rolled back to its original state.

Testing the Trigger

To test run the Trigger, select the Trigger 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 the Trigger.

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After installing nomachine, if you get an error connecting whereby nomachine errors out after  "Negotiating link parameters"
 

When installing nomachine on redhat 5.3 64-bit be sure to:

  1. Make sure you have installed the 64-bit packages as the 32-bit ones will not work.
  2. add the hostname to /etc/hosts
  3. Check "Disable encryption of all traffic" (in configuration / advanced tab)
On Centos 32-bit:
  1. add the hostname to /etc/hosts
  2. make sure the host IP is not specified as 127.0.0.1 line
  3. Uncheck "Disable encryption of all traffic" (in configuration / advanced tab)
 
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After split brain has been detected, one node will always have the resource in a StandAlone connection state. The other might either also be in the StandAlone state (if both nodes detected the split brain simultaneously), or in WFConnection (if the peer tore down the connection before the other node had a chance to detect split brain).

At this point, unless you configured DRBD to automatically recover from split brain, you must manually intervene by selecting one node whose modifications will be discarded (this node is referred to as the split brain victim). This intervention is made with the following commands:

# drbdadm secondary resource 
# drbdadm disconnect resource
# drbdadm -- --discard-my-data connect resource


On the other node (the split brain survivor), if its connection state is also StandAlone, you would enter:

# drbdadm connect resource


You may omit this step if the node is already in the WFConnection state; it will then reconnect automatically.

If all else fails and the machines are still in a split-brain condition then on the secondary (backup) machine issue:

drbdadm invalidate resource
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There's a nice article on IBM developerworks describing how to package software using RPM. You can read it here.

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If you are running your Redhat/Centos or Fedora machine in an enterprise environment you may be sitting behind a network proxy server like squid.

If you try and update or install software it will fail with timeouts or errors contacting the repository mirrors.

To configure YUM to work with your proxy server you need to add the following line to your /etc/yum.conf file.

Anonymous proxy configuration:
proxy=http://yourproxyip:port/

If your proxy server requires authentication add the following lines to your /etc/yum.conf file instead.

proxy=http://yourproxyip:port/
proxy_username=youruser
proxy_password=yourpassword

 You will be able to update and install software now, give it a go!

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