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Foglight for Virtualization Enterprise Edition 8.9.3 - Web Component Guide

Introducing the Web Component Framework The Web Component Framework Configuring Views and Context Queries Functions Bindings Additional Components

Java Functions

A JavaTM Function definition is used to execute a Java method and return a result. It can optionally have parameters to the Java method. Java Functions are meant to be used to call user-defined Java code that has been deployed to the Foglight® server.

Using the editor, these attributes can be specified:

•
The fully-qualified name of the class containing the Java method to invoke. In order for the class to be loaded, it needs to exist on the server's classpath or in a Jar file that WCF will be notified about when loaded or unloaded. In Foglight, you would normally accomplish this by adding the jars with your classes as a wcf-task component in your cartridge.
•
The name of the method to invoke. The method must be public, static, have one parameter of type FunctionHelper and not return void.
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The parameters (which are named, have a type and declare whether they are a list or not)
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The output type (including whether it is a list or not)

When a Java Function is executed, the parameter values are evaluated (if they are bindings) and passed into the method and the result is returned. If the declared output type is not a list and the result is not of the declared type, null is returned instead. If the declared output type is a list, then the result is checked to ensure it is a list, but the list items are not checked to determine whether they are of the declared output type.

 
* 
NOTE: It is possible that a Java Function can be called by multiple threads so implementations need to be thread-safe.
Example of a method suitable for use as a Java Function:

This is the signature of the method for the Check Permission Java Function definition available in the Dashboard Support > Common module:

public static boolean checkPermission(FunctionHelper helper)

Map Functions

A Map Function definition consists of a set of keys and their corresponding mapped values. The function expects a key as its input value and the value corresponding to the key is returned.

An example of a Map Function:

Figure 33. Map function example

Using the editor, these attributes can be specified:

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Input type
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Map entry keys and values
•
Output type (including whether or not it is a list)
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Map default value

When a Map Function is executed, the keys are checked (and evaluated if they are bindings) in order, and when one result equals the input, the corresponding Map value is returned (if it is a binding, it is evaluated and then returned). If no matching key is found, and the Map Default Value is specified, the function returns this default value. If no matching key is found, and the Map Default Value is not set, the function returns Null.

The editor ensures that all the keys of the map are the same type as the input type and that all the values of the map are the same type as the output type. Also, the map values must match the declaration of whether or not the output is a list.

One map entry having a null key is allowed. To specify a null key, simply do not set the map key.

Script Functions

A Script Function definition is used to execute a script and return a result. It can optionally take inputs to the script.

An example of a Script Function:

Figure 34. Script function example

Using the editor, these attributes can be specified:

•
Parameters (which are named, have a type, and declare whether or not they are a list). These parameters are used by the function and must be set in the binding that invokes the function.
•
Script text. The Groovy code is entered here.
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Output type (including whether or not it is a list). This is the return type for the Groovy function. Normally this is a String status message.

When a Script Function is executed, the inputs are evaluated (if they are bindings) and passed into the script. The script is executed via the ScriptService and the result is returned.

 
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NOTE: The ScriptService is used by the Web Component Framework for evaluating Function definitions of type Script or Map with Script.

Script with Map Functions

A Script with Map Function definition is used to execute a script that accepts a map key and the corresponding map value is returned. The script can optionally take inputs.

An example of a Script with Map Function:

Figure 35. Script with Map Function example

Using the editor, these attributes can be specified:

•
Inputs (which are named, have a type and declare whether or not) they are a list
•
Script text
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Map input type
•
Map entry keys and values
•
Output type (including whether or not it is a list)
•
Map default value

When a Script with Map Function is executed, the inputs are evaluated (if they are bindings) and passed into the script. The script is executed via the ScriptService. The script result is then checked against the map keys (which are evaluated if they are bindings) in order, and when one result equals the script result, the corresponding Map value is returned (if it is a binding, it is evaluated and then returned). If no matching key is found, and the Map Default Value is specified, the function returns this default value. If no matching key is found, and the Map Default Value is not set, the function returns Null.

The editor ensures that all the keys of the map are the same type as the map input type and that all the values of the map are the same type as the output type. Also, the map values must declaration of whether or not the output is a list.

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