Calling Functions

This section explains how to programmatically list and call context functions.

There are several ways to get a list of functions from a Context:

• getFunctionDefinitions() - this method will return the list of all functions in a context
• getFunctionDefinitions(CallerController caller) - this method will return the list of functions accessible by the caller
• getFunctionDefinitions(String group) - this method will return the list of functions belonging to the certain group of its subgroups
• getFunctionDefinitions(CallerController caller, String group) - this method will return the list of functions belonging to the certain group and accessible by the caller

List<FunctionDefinition> functions = context.getFunctionDefinitions(ContextUtils.GROUP_REMOTE); // Finding all functions in group "remote"

To retrieve a single function definition by its name call getFunctionDefinition(String name) method. The method getFunctionDefinition(String name, CallerController caller) will return a definition or null if function is not accessible by caller.

To call a function, use Context.callFunction() method. It accepts the following arguments: name of function to call, optional instance of CallerController that incorporates permissions of calling side (see Dealing with Access Permissions for details), and optional function parameters.

There are two ways to specify function input parameters:

• By supplying a pre-built DataTable object. This object can be programmatically created from scratch using format obtainable via FunctionDefinition.getInputFormat().
• By supplying individual cell values of function input data table.

The callFunction() method returns a DataTable representing function output.

Example 1 - calling function by supplying a pre-built data table:

DataTable input = new SimpleDataTable(context.getFunctionDefinition("sendSms").getInputFormat());

input.addRecord().addString("+12345678900").addInt("First message"); // Adding a record
input.addRecord().addString("+98765432100").addInt("Second message"); // Adding another one

DataTable output = context.callFunction("sendSms", input); // Calling function

Example 2 - calling function by supplying a list of input table cell values:

DataTable output = context.callFunction("sendSms", "12345678900", "First message"); // Supplying cell values for the first record of function input table

Interfaces located in com.tibbo.aggregate.common.server package provide string constants matching names of most server context functions and their input/output fields.

Using those constants is always preferred to using string constants defined in your own code. This will ensure error-proof code if some functions or fields will get renamed or relocated in the future versions of Iotellect Server.

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