This chapter explains how to develop custom-defined functions and use them in Essbase formulas and calculation scripts. Custom-defined functions are written in the Java programming language and enable you to create calculation functions not otherwise supported by the Essbase calculation scripting language.
Essbase does not provide tools for creating Java classes and archives. This chapter assumes that you have a compatible version of the Java Development Kit (JDK) and a text editor installed on the computer you will use to develop custom-defined functions. For more information on compatible versions of Java, see the Essbase Installation Guide.
For more examples of custom-defined functions, see the Technical Reference in the docs directory.
Use these sections to create and use custom-defined functions:
You can find out information about existing custom-defined functions using Application Manager:
No custom-defined functions are displayed until they have been created and registered. Essbase does not supply sample custom-defined functions.
Tip: You can also view information about custom-defined functions using MaxL. For instructions, see Verifying Custom-Defined Functions.
There are several steps required to create a custom-defined function:
The basis of a custom-defined function is a Java class and method created by a database administrator or Java programmer to perform a particular type of calculation. Creating and testing these Java classes and methods is the first step toward creating a custom-defined function.
You can create more than one method in a class for use as a custom-defined function. In general, it is recommended that you create all the methods you want to use as custom-defined functions in a single class. However, if you want to add new custom-defined functions that are not going to be used across all applications on OLAP Server, create them in a new class and add them to OLAP Server in a separate .jar file.
When creating multiple Java classes that contain methods for use as custom-defined functions, verify that each class name is unique. Duplicate class names will cause methods in the duplicate class not to be recognized, and you will be unable to register those methods as custom-defined functions.
After creating the Java classes and methods for custom-defined functions, test them using test programs in Java. When you are satisfied with the output of the methods, install them on OLAP Server and register them in a single test application. Do not register functions globally for testing, because this makes it more difficult to update them if you find problems.
Methods in custom-defined functions can have any combination of the following supported data types as input parameters:
Data Types Allowed As Input Parameters |
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CalcBoolean is an Essbase-specific data type that can include three values: TRUE, FALSE, and #MISSING. For more information about the other listed data types, see the documentation for the Java Development Kit.
The method return data type can be void or any of the preceding data types. Returned data types are converted to Essbase-specific data types. Strings are mapped to a string type. Boolean values are mapped to the CalcBoolean data type. All other values are mapped to a double type.
Note: Double variables returned with infinite or Not-a-Number values are not supported by Essbase. If these values are returned from a Java program, they may not be recorded or displayed correctly in Essbase. Double variables should be checked for infinite or Not-a-Number values and set to finite values before being returned to Essbase. For more information, see the entry for the class, Double, in the documentation for the Java Development Kit.
For more examples of Java custom-defined functions, see the MaxL statement create function in the Technical Reference in the docs directory.
Essbase requires that you have these security permissions:
Custom-defined functions are registered with one of two scopes: local (application) or global (OLAP Server). When you register a local custom-defined function, it is available only in the application in which it was registered. When you register a global custom-defined function, it is available to all applications on the OLAP Server on which it was registered.
When developing and testing custom-defined functions, make sure to register and test new functions locally within a test application. You should never register custom-defined functions globally until you have thoroughly tested them and are ready to use them as part of a production environment.
When you register a custom-defined function in Essbase, you give the function a name. This name is used in calculation scripts and formulas and is distinct from the Java class and method name used by the function.
Remember these requirements when you create function names:
For more information about registering custom-defined functions, see Registering Custom-Defined Functions.
To create a Java class for a custom-defined function, use this procedure:
public class CalcFunc { public static double sum (double[] data) { int i, n = data.length; double sum = 0.0d; for (i=0; i<n; i++) { double d = data [i]; sum = sum + d; } return sum; } }
>javac CalcFunc.java
When you install Java classes on OLAP Server, you must first compile the classes into a Java Archive (.jar) file, and then copy the .jar file to a specific location on the computer running OLAP Server.
Note: You must either stop and restart Essbase applications or stop and restart OLAP Server when you install new .jar files.
To create a .jar file from a .class file and install it on an OLAP Server:
>jar cf CalcFunc.jar CalcFunc.class
If the .jar file is placed in another location, you must modify the CLASSPATH variable to include the full path and file name for the .jar file.
After you have compiled the Java classes for custom-defined functions into .jar files and installed the .jar files on OLAP Server, you must register the custom-defined function before you can use them in calculation scripts and formulas.
When you register a global custom-defined function, all of your Essbase applications can use it. Be sure you test custom-defined functions in a single application (and register them only in that application) before making them global functions.
Caution: Do not register global functions for testing, because this makes it more difficult to change them if you find problems.
To register a custom-defined function using MaxL, use this procedure:
MAXL> create function Sample.'@JSUM' 2> as 'CalcFunc.sum' 3> spec '@JSUM(memberRange)' 4> comment 'adds list of input members';The prefix Sample. before the name of the function assigns the custom-defined function to the application Sample, so the function will be available only within that application.
MAXL> create function '@JSUM' 2> as 'CalcFunc.sum'; 3> spec '@JSUM(memberRange)' 4> comment 'adds list of input members';The AppName. prefix is not included in the name of the function. The lack of a prefix makes a function global.
Note: Specifying input parameters for the Java method is optional. If you do not specify input parameters, Essbase reads them from the method definition in the Java code. However, if you are registering two or more custom-defined functions with the same method name but with different parameter sets, you must register each version of the function separately, specifying the parameters for each version of the function.
For more detailed information on the create function statement grammar, see the MaxL section of the Technical Reference in the docs directory. For rules about naming custom-defined functions, see Naming Custom-Defined Functions.
To register custom-defined functions using Application Manager, use this procedure:
This example uses information about the sample class created in Registering Custom-Defined Functions Using MaxL. If you need help filling in the values, review that section.
After registering custom-defined functions, you can determine whether a function has been registered successfully and whether it is registered locally or globally. You can use MaxL or Application Manager.
To check the registration of custom-defined function on OLAP Server using MaxL, use this procedure:
MAXL> display function Sample;This statement displays a list of all functions registered for the named application (Sample) and any registered global functions. The display function statement lists global functions without an application name to indicate that they are global. If the application contains a function with the same name as a global function, only the local function is listed.
To check the registration of custom-defined functions on OLAP Server using Application Manager, use this procedure:
If your function has been successfully registered, it will appear in this list.
After registering custom-defined functions, you can use them like native Essbase calculation commands. Functions you registered locally-using the AppName. prefix on the function name-are only available for use in calculation scripts or formulas within the application in which they were registered. If you registered the custom-defined functions globally, then the functions are available to all calculation scripts and formulas on the OLAP Server where the functions are registered.
For more information about registering custom-defined functions, see Registering Custom-Defined Functions.
To use a registered custom-defined function:
"New York" = @JSUM(@LIST(2.3, 4.5, 6.6, 1000.34));Use this calculation script with the Sample Basic sample database, or replace "New York" with the name of a member in a test database.
For more information about creating and running calculation scripts, see Developing Calculation Scripts. For more information about creating and running formulas, see Developing Formulas.
When you update a custom-defined function, there are two major issues to consider:
The answers to these questions determine the procedure for updating the custom-defined function.
For information on determining whether a custom-defined function is local or global, see Verifying Custom-Defined Functions.
To update a custom-defined function, in most cases, you must replace the .jar file that contains the code for the function, and then re-register the function. However, if the signature of the custom-defined function-the Java class name, method name and input parameters-have not changed and the function has only one set of input parameters (it is not an overloaded method), you can simply replace the .jar file that contains the function. In either situation, you must stop and restart the Essbase application or OLAP Server where the custom-defined function is registered, depending on whether it is a local or global function.
Note: The following procedure is effective only if the signature of the custom-defined function-the Java class name, method name, and input parameters for the custom-defined function-has not changed.
To update a custom-defined function whose signature has not changed:
Local custom-defined functions are registered with an AppName. prefix on the function name and can be used only within the application where they were registered. To update a local custom-defined function, you must stop and restart the Essbase application where the function is registered.
To update a local custom-defined function:
MAXL> create or replace function sample.'@JSUM' 2> as 'CalcFunc.sum';Note: This step can also be performed by using the Application Manager Custom Defined Function Manager. Start the server, Application Manager and application, and select File > Custom Defined Function Manager from the menu. Select a function from the list displayed and click Edit to make changes.
Global custom-defined functions are registered without an AppName. prefix on the function name and are available in any application running on the OLAP Server where they are registered. To update a global custom-defined function, you must stop and restart all applications on OLAP Server.
Global custom-defined functions can be used in calculation scripts and formulas across OLAP Server, so you should verify that no calculation scripts or formulas are using a global custom-defined function before updating it.
Caution: Only a database administrator should update global custom-defined functions.
To update a global custom-defined function:
MAXL> create or replace function '@JSUM' 2> as 'CalcFunc.sum';Note: This step can also be performed by using the Application Manager Custom Defined Function Manager. Start the server and Application Manager, and select File > Custom Defined Function Manager from the menu. Select a function from the list displayed and click Edit to make changes.
When removing a custom-defined function, you must first determine whether the function is registered locally or globally to identify the security permissions required:
Before removing custom-defined functions, you should verify that no calculation scripts or formulas are using them. Global custom-defined functions can be used in calculation scripts and formulas across OLAP Server, so you must verify that no calculation scripts or formulas on OLAP Server are using a global custom-defined function before removing it.
For information on determining whether a custom-defined function is local or global, see Verifying Custom-Defined Functions.
Local custom-defined functions are registered with an AppName. prefix on the function name and can only be used within the application where they are registered. When you remove a local custom-defined function, the Essbase application where the function is registered must be stopped and restarted.
To remove a local custom-defined function:
MAXL> drop function Sample.'@JSUM';Note: This step can also be performed by using the Application Manager Custom Defined Function Manager. Start the server and Application Manager, and select File > Custom Defined Function Manager from the menu. Select a function from the list displayed and click Delete to remove the custom-defined function.
Global custom-defined functions are registered without an AppName. prefix on the function name and are available in any application running on OLAP Server where they are registered. When you remove a global custom-defined function, all running Essbase applications must be stopped and restarted.
Global custom-defined functions can be used in calculation scripts and formulas across OLAP Server, so you should verify that no calculation scripts or formulas are using a global custom-defined function before removing it.
Caution: Only a database administrator with supervisor permission can remove global custom-defined functions. Removal of global custom-defined functions should only be performed when no users are accessing Essbase databases and no calculation routines are being performed.
To remove a global custom-defined function:
MAXL> drop function '@JSUM';Note: This step can also be performed by using the Application Manager Custom Defined Function Manager. Start the server and Application Manager, and select File > Custom Defined Function Manager from the menu. Select a function from the list displayed and click Delete to remove the custom-defined function.
The ability to create and run custom-defined functions is provided as an extension to the Essbase calculator framework. When you use custom-defined functions, consider how their use affects memory resources and calculator performance.
Because custom-defined functions are implemented as an extension of the Essbase calculator framework, you can expect custom-defined functions to operate less efficiently than functions that are native to the Essbase calculator framework. In tests using a simple addition function running in the Java Runtime Environment 1.3 on the Windows NT 4.0 platform, the Java function ran 1.8 times (about 80%) slower than a similar addition function performed by native Essbase calculation commands.
To optimize performance, limit use of custom-defined functions to calculations that you cannot perform with native Essbase calculation commands, particularly in applications where calculation speed is a critical consideration.
Use of the Java Virtual Machine (JVM) and Java API for XML Parsing has an initial effect on the memory required to run Essbase. The memory required to run these additional components is documented in the memory requirements for Essbase. For more information about memory requirements, see the Essbase Installation Guide.
Beyond these start-up memory requirements, the Java programs you develop for custom-defined functions sometimes require additional memory. When started, the JVM for Win32 operating systems immediately allocates 2 MB of memory for programs. This allocation is increased according to the requirements of the programs that are then run by the JVM. The default upper limit of memory allocation for the JVM on Win32 operating systems is 64 MB. If the execution of a Java program exceeds the default upper limit of memory allocation for the JVM, the JVM generates an error. For more information about JVM memory management and memory allocation details for other operating systems, see the Java Development Kit documentation.
Considering the default memory requirements of the JVM and the limitations of the hardware on which you run servers, carefully monitor your use of memory. In particular, developers of custom-defined functions should be careful not to exceed memory limits of the JVM when creating large objects within custom-defined functions.
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