Administration Guide

Configuring Liquid Data Applications

This chapter describes how to configure application-level settings for BEA Liquid Data for WebLogic. The chapter contains the following sections:

• General Application Settings
• Guidelines for Setting the Thread Count
• Monitoring Applications
• Terminating Query Execution
• Using Administrative Properties
• Setting the Transaction Isolation Level

 

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General Application Settings

You can view and configure run-time application-wide settings, including access control, cache settings, server resources (including thread usage), and log levels.

To specify general application settings:

Click the name of the Liquid Data application node in the Navigation pane of the Liquid Data Console.

The General settings page appears, as illustrated in Figure 5-1. Note that you must be logged into the console using a user name with administrator privileges.

Figure 5-1 General Application Settings Page




 

Specify settings, as appropriate.
Click Apply to save the settings.

Table 5-1 lists the application settings available under the General tab.

Table 5-1 Liquid Data Server Configuration Settings  

Section	Field	Description
Access Control	Check Access Control	Specifies whether the configured security policy settings will be enforced for the application.
	Allow default anonymous access	Enables access to the application by default (unless a more specific policy blocks it). If enabled, all users can access resources by default, even unauthenticated users. Disallowing default anonymous access disables access to the application by default (unless a more specific policy permits it). The anonymous access option works only with the WebLogic Authorization provider.
Cache	Enable Cache	Enables or disables (default) the caching of query results for stored queries. To enable results caching, enable (check) this check box. To disable results caching, clear (uncheck) this check box. For more information about caching, see Configuring the Query Results Cache.
	Cache data source name	The JNDI data source name for the database where the cache is stored.
	Cache table name	The name of the database table where cached data is stored. The default table name is <appName>_CACHE.
Server Resources	Max number of query plans cached	A query plan is a compilation of a query. The optimal number of query plans cached depends on the size of the queries. You will need to monitor the memory usage and performance of your server to determine whether to change this setting.
	Max threads for application	The maximum number of threads in the Liquid Data server pool used to handle query requests. The default setting is 20. The minimum setting is 1. If the specified value is invalid, the server uses the default value of 20. Note: The maximum threads value that you specify here does not affect the WebLogic Server server thread pool. The value specified here applies only to the thread pool created and used by the Liquid Data query engine for processing requests on application view, web service, or custom function data sources. For more information on configuring thread counts, see Guidelines for Setting the Thread Count.
	Max threads for one query	The maximum number of threads allowed for a single query. Use this to limit the number of threads spawned by a single query. The actual number of threads used will not exceed the maximum number of threads specified in Maximum Threads, regardless of the Maximum Number of Threads Per Query setting. The default setting is 4. The minimum setting is 1. If the specified value is invalid, the server uses the default value of 4. Note: The maximum threads value that you specify here does not affect the WebLogic Server server thread pool. The value specified here applies only to the thread pool created and used by the Liquid Data query engine for processing requests on application view and web service data sources. For more information on configuring thread counts, see Guidelines for Setting the Thread Count.
Log Level	Logging	The verbosity of the events logged. The options include the following: Error. Runtime exceptions. Notice. Possible errors that do not affect runtime operation, as well as error level events. Information. Start/stop events, unsuccessful access attempts, query execute times, and so on, as well as error and notice level events. The log file is in the following location: <BeaHome>\user_projects\domains\<domainName>\ <domainName>.log


 

 

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Guidelines for Setting the Thread Count

The optimal thread count settings you configure depends on the physical resources of the machine on which you deploy Liquid Data, the anticipated load, and the type of application you are deploying. Increasing the number of threads can accelerate processing, but since each thread consumes memory, you must achieve a balance based on the available resources.

Use the following general guidelines for settings the thread count:

• The maximum threads set for an application should not exceed the WebLogic Server thread count.
• The total maximum application thread counts for all deployed applications should not be significantly greater than the total WebLogic Server thread count.

Liquid Data only uses the thread pool for acquiring web service calls; threads are only spawned when web services are invoked by queries. Therefore, an application that does not rely on web service content can have a relatively low thread count setting.

For more information on tuning performance for the WebLogic Server and applications, see the following:

http://download.oracle.com/docs/cd/E13222_01/wls/docs81/perform/index.html

 

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Monitoring Applications

You can view statistics and status information for a Liquid Data application, particularly relating to query activities, using the Monitor tab. You can also monitor active application processes, displaying information such as the user who initiated the process, the time is has been running, and the number of cached entries for the process type.

To monitor an application:

Click the name of the Liquid Data application node in the Navigation pane of the Liquid Data Console.

The General settings page appears. Note that you must be logged into the console using a user name with administrator privileges.

Click the Monitor tab.

The monitoring information for the application appears, as illustrated in Figure 5-2.

Figure 5-2 Monitor Tab




 


 

Table 5-2 describes the information displayed in the Monitor tab.

Table 5-2 Monitoring Statistics for the Liquid Data Server 

Section	Field	Description
Monitoring information for ... Application	Active Queries	The number of query instances currently running.
	Cached Queries	The total number of XQuery plans currently cached in memory. A cache entry is made for each distinct invocation of the named function with different input parameters.
	Active Updates	The number of update functions currently running.
Monitoring information for functions of ... Application	Function Name	The name of the function for which the statistics apply.
	Instance ID	The unique identifier assigned to the process by the Liquid Data runtime components.
	User Name	For secured data services, the name of the user that invoked the service.
	Running Time	The amount of time the query has been running in milliseconds.
	Number of Cached Entries	The number of instances of the query in cache. A cache entry is made for each distinct invocation of the named function with different input parameters.

 

 

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Terminating Query Execution

Once invoked, a data service function runs until either it gets a result or a time-out expires (assuming a time-out period is set). The time-out setting enables you to specify, in the query, the maximum time a query should wait for unresponsive data sources.

In some cases, it may be necessary to cancel the execution of a function. The Monitor tab enables you to view and cancel currently running queries. The page also displays the user associated with the query and cache information.

When you terminate a process, the operation in progress finishes, then the process completes without executing subsequent nodes.

Note: The submit query is rolled back only in cases when you are using the XA driver.

To terminate function execution:

Click the name of the application in the Navigation pane.

The General settings page appears. (Note that you must be logged into the console using a user name with administrator privileges.)

Click the Monitor tab.

The list of functions currently running appears in the functions table.

Select the check box in the Terminate Query column for the appropriate function, and click Apply to terminate the query.

A confirmation dialog box is displayed.

Click OK to confirm, or Cancel to dismiss the dialog and cancel the action.

Note: Terminating a query triggers a weblogic.xml.query.exceptions.XQuerySystemException on the client.

 

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Using Administrative Properties

An administrative property is a user-defined property that you can configure using the Liquid Data Console. The value of an administrative property can be used in XQuery functions, either in data service functions or security XQuery functions.

Note: For information on security XQuery functions, see Securing Liquid Data Resources.

An administrative property is a convenient way of having function parameters that can be easily changed by the administrator, without having to modify the body of either the data service function or security XQuery function.

The administrative property has application scope—any data service in the application can use the property value. The property value can be accessed using XQuery with the BEA function get-property(). The function takes the name of the property as an argument and returns the value as a string. It also takes an argument that serves as the default value for the parameter. This value is used if the property is not configured in the console.

The following shows a complete example of an XQuery Function Library function using an administrative property:

declare function f1:getMaximumAccountViewable() as xsd:decimal { 
   let $amount := fn-bea:get-property("maxAccountValue", "1000.00") 
                                   cast as xsd:decimal
   return $amount
};

To manage administrative properties:

Click the name of the application in the Navigation pane.

The General Settings page appears. (Note that you must be logged into the console using a user name with administrator privileges.)

Click the Administrative Properties tab.

The list of property names currently defined appears in the table, as illustrated in Figure 5-3.

Figure 5-3 Administrative Properties Tab




 


 

Table 5-3 describes the information displayed in the Administrative Properties tab:

Table 5-3 Administrative Properties

Column	Description
Property Name	The name of the administrative property.
Property Value	The current value of the property.
Delete Property	A Trash icon enabling you to delete the property.

 

To add a property, complete the following:
Enter a name for the property in the Property Name field.

The name must match the name property passed to the get-property() function used to access the properties value. For example:

fn-bea:get-property("maxAccountValue", "1") 

Optionally, enter an initial value for the property.

You can change this value later, if required.

Click Add Property.

The property appears in the list.

To change a property value:
Enter a new value in the Property Value field (in the list of currently defined properties).
Click Apply.
To delete a property:
Click the delete icon ( ) next to the property.
Confirm the delete when prompted.

Note that the default value for the property is used in any get-property() call using the deleted property.

 

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Setting the Transaction Isolation Level

In some instances, Liquid Data may not be able to read data from a database table because another application has locked the table, causing queries issued by Liquid Data to be queued until the application releases the lock. To prevent this, you can set the transaction isolation to read uncommitted in the JDBC connection pool on your WebLogic Server.

To set the transaction isolation level:

Start the Administration Console in a web browser by opening the following URL:

http://<HostName>:<Port>/console

For example, to start the Administration Console for a local instance of WebLogic Server (running on your own machine), type the following URL in a web browser address field:

http://localhost:7001/console/

Expand Services —>JDBC —>Connection Pools under the domain in which the Liquid Data application runs, and click the name of the connection pool you want to configure.

The Connections tab appears, as illustrated in Figure 5-4.

Figure 5-4 Connections Tab




 

Click Show in the Advanced Options section of the page.

The page expands to include the Advanced Options section.

Scroll to the bottom of the section, and enter the following in the Init SQL field:

SQL SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED

Click Apply.