Developing Functions in Java (Using Eclipse)

Function Syntax

• Scope: It must be defined as public for the function that FunctionGraph invokes to execute your code.
• Return parameter: user-defined output, which is converted into a character string and returned as an HTTP response. The HTTP response is a JSON string.
• Function name: user-defined function name.
• User-defined parameter: FunctionGraph supports only one user-defined parameter. For complex parameters, define them as an object and provide data through JSON strings. When invoking a function, FunctionGraph parses the JSON strings as an object.
• Context: runtime information provided for executing the function. For details, see SDK APIs.

Java Initializer

• Java 8
• Java 11
• Java 17
• Java 21

• Function name

  The function name my_initializer must be the initializer function name specified for a function.

  For example, if the initializer is named com.Demo.my_initializer, FunctionGraph loads the my_initializer function defined in the com.Demo file.

• context

  The context parameter contains the runtime information about a function. For example, request ID, temporary AK, and function metadata.

SDK APIs

• Context APIs

  The context APIs are used to obtain the context, such as agency AK/SK, current request ID, allocated memory space, and number of CPUs, required for executing a function.

  Table 1 describes the context APIs provided by FunctionGraph.

  Table 1 Context methods

  Method	Description
  getRequestID( )	Obtains a request ID.
  getRemainingTimeInMilligetRunningTimeInSecondsSeconds ( )	Obtains the remaining running time of a function.
  getAccessKey( )	Obtains the AK (valid for 24 hours) of an agency. If you use this method, you need to configure an agency for the function. NOTE: FunctionGraph has stopped maintaining the getAccessKey API in the Runtime SDK. You cannot use this API to obtain a temporary AK.
  getSecretKey( )	Obtains the SK (valid for 24 hours) of an agency. If you use this method, you need to configure an agency for the function. NOTE: FunctionGraph has stopped maintaining the getSecretKey API in the Runtime SDK. You cannot use this API to obtain a temporary SK.
  getSecurityAccessKey( )	Obtains the SecurityAccessKey (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function.
  getSecuritySecretKey( )	Obtains the SecuritySecretKey (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function.
  getSecurityToken( )	Obtains the SecurityToken (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function.
  getUserData(string key)	Uses keys to obtain the values passed by environment variables.
  getFunctionName( )	Obtains the name of a function.
  getRunningTimeInSeconds ( )	Obtains the timeout of a function.
  getVersion( )	Obtains the version of a function.
  getMemorySize( )	Obtains the allocated memory.
  getCPUNumber( )	Obtains CPU usage of a function.
  getProjectID( )	Obtains a project ID.
  getPackage( )	Obtains a function group, that is, an app.
  getToken( )	Obtains the token (valid for 24 hours) of an agency. If you use this method, you need to configure an agency for the function.
  getLogger( )	Obtains the logger method provided by the context. By default, information such as the time and request ID is output.

  Notice

  Results returned by using the getToken(), getAccessKey(), and getSecretKey() methods contain sensitive information. Exercise caution when using these methods.

• Logging API

  Table 2 describes the logging API provided in the Java SDK.

  Table 2 Logging API

  Method	Description
  RuntimeLogger()	Records user input logs using the method log(String string).

Developing a Java Function

1. Create a function project.
   1. Configure Eclipse and create a Java project named JavaTest, as shown in Figure 1.

      Figure 1 Creating a project

      
      
   2. Add a dependency to the project.

      Download the to a local development environment, and decompress the SDK package, as shown in Figure 2.

      Figure 2 Decompressing the downloaded SDK

      
      

   3. Configure the dependency.

      Create a folder named lib in the project directory, copy the Runtime-1.1.3.jar file in the SDK package to the lib folder, and add the JAR file as a dependency of the project, as shown in Figure 3.

      Figure 3 Configuring the dependency

      
      

2. Create a function.
   1. Create a package named com.demo, and then create a class named TriggerTests under the package, as shown in Figure 4.

      Figure 4 Creating a package named com.demo

      
      
   2. Define the function handler in TriggerTests.java.

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      26package com.demo;
      
      import java.io.UnsupportedEncodingException;
      import java.util.HashMap;
      import java.util.Map;
      
      import com.services.runtime.Context;
      import com.services.runtime.entity.smn.SMNTriggerEvent;
      import com.services.runtime.entity.timer.TimerTriggerEvent;
      
      public class TriggerTests {
      
          public String smnTest(SMNTriggerEvent event, Context context){
              System.out.println(event);
              return "ok";
          }
      
          }
      
          public String timerTest(TimerTriggerEvent event, Context context){
              System.out.println(event);
              return "ok";
          }
      
      
      }
      
      

3. Package the project files.
   1. Right-click the JavaTest project and choose Export, as shown in Figure 5.

      Figure 5 Packaging the project files

      
      
   2. Export the project to a directory as a JAR file, as shown in Figure 6 and Figure 7.

      Figure 6 Selecting a format

      
      

      Figure 7 Specifying the destination path

      
      

4. Log in to the FunctionGraph console, create a Java function, and upload the code package.
5. Test the function.
   1. Create a test event.

      Select Timer and click Save.

   2. Click Test.

      The function execution result consists of three parts: function output (returned by callback), summary, and logs (output by using the console.log or getLogger() method).

   3. Create a timer trigger.
   4. Access the API URL.

      Change the handler to com.demo.TriggerTests.smnTest and change the event template to smn-event-template, and execute the function.

6. Use a user-defined parameter in the Java code.

   Create a Person class in the project, as shown in Figure 8.

   Figure 8 Creating a Person class

   
   

   Create a class named PersonTest.java, and add a handler function to the class, as shown in Figure 9.

   Figure 9 Creating a class named PersonTest.java

   
   

   After exporting the new package, upload it to the function, change the function handler to com.demo.PersonTest.personTest, and click Save.

   In the Configure Test Event dialog box, select blank-template, enter a test event, and click Save.

   Click Create, and then click Test.

Execution Result

{
  "errorMessage": "",
  "stackTrace": []
}