Developing an Event Function

Function Syntax

Use the following syntax when creating a handler function in PHP 7.3:

function handler($event, $context)

• $handler: name of the function that FunctionGraph invokes to execute your code. The name must be consistent with that you define when creating a function.
• $event: event parameter defined for the function. The parameter is in JSON format.
• $context: runtime information provided for executing the function. For details, see SDK APIs.
• Function handler: index.handler.
• The function handler is in the format of [File name].[Function name]. For example, if you set the handler to index.handler in your function, FunctionGraph will load the handler function defined in the index.php file.

PHP Initializer

FunctionGraph supports the following PHP runtime:

• Php 7.3 (runtime = Php7.3)

Initializer syntax:

[File name].[Initializer name]

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

To use PHP to build initialization logic, define a PHP function as the initializer. The following is a simple initializer:

<?php
Function my_initializer($context) {
    echo 'hello world' . PHP_EOL;
    }
?>

SDK APIs

The following table describes the context methods provided by FunctionGraph.

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

Developing a PHP Function

Perform the following steps to develop a PHP function:

1. Create a function.
   1. Write code for printing text helloworld.

      Open the text editor, compile a HelloWorld function, and save the code file as helloworld.php. The code is as follows:

      1 2 3 4

      <?php function printhello() { echo 'Hello world!'; }

   2. Define a FunctionGraph function.

      Open the text editor, define a function, and save the function file as index.php under the same directory as the helloworld.php file. The function code is as follows:

      1 2 3 4 5 6 7 8

      <?php include_once 'helloworld.php'; function handler($event, $context) { $output = json_encode($event); printhello(); return $output; }

      

      1. FunctionGraph can return only the following types of values:
         • Null: The HTTP response body is empty.
         • string: The content in this string is the body of an HTTP response.
         • Other: FunctionGraph returns a value for JSON encoding, and uses the encoded object as the body of an HTTP response. The Content-Type header of the HTTP response is set to text/plain.
      2. For details about the constraints for the APIG event source, see Base64 Decoding and Response Structure.

2. Package the project files.
   After creating the function project, you get the following directory. Select all files under the directory and package them into the fss_examples_php7.3.zip file, as shown in Figure 1.

   Figure 1 Packaging the project files
   

   

   In this example, the function project files are saved under the ~/Code/ directory. Select and package all files under the directory to ensure that the index.php file, the handler of your FunctionGraph function, is under the root directory when the fss_examples_php7.3.zip file is decompressed.

3. Create a FunctionGraph function and upload the code package.
   Log in to the FunctionGraph console, create a PHP function, and upload the fss_examples_php7.3.zip file, as shown in Figure 2.

   Figure 2 Uploading the code package
   

   

   • The index of the handler must be consistent with the name of the file created in Step 1 (2), because the file name will help to locate the function file.
   • The handler is a function name, which must be the same as that in the index.php file created in Step 1 (2).
   • After you upload the fss_examples_php7.3.zip file to OBS, when the function is triggered, FunctionGraph decompresses the file to locate the function file through index and locate the function defined in the index.php file through handler, and then executes the function.

   In the navigation pane on the left of the FunctionGraph console, choose Functions > Function List. Click the name of the function to be set. On the function details page that is displayed, choose Configuration > Basic Settings and set the Handler parameter, as shown in Figure 3. The parameter value is in the format of index.handler. The values of index and handler can be customized.

   Figure 3 Handler parameter
   

4. Test the function.
   1. Create a test event.
      On the function details page that is displayed, click Configure Test Event. Configure the test event information, as shown in Figure 4, and then click Create.

      Figure 4 Configuring a test event
      
   2. On the function details page, select the configured test event, and click Test.

5. View the function execution result.

   The function execution result consists of three parts: function output (returned by return), summary, and logs (output by using the echo method).

Execution Result

The execution result consists of the function output, summary, and log output.

{
    "errorMessage": "",
    "errorType": "",
    "stackTrace": {}
}