Protobuf implementations

There are two implementations that are available for PHP:

C: Uses the Protobuf PHP extension which gives better performance.
PHP: Uses the google/protobuf PHP package which is easier to implement.

We recommend using the C implementation if you can, but PHP may be needed in some cases (such as when limited by security or technical constraints).

The PHP implementation is automatically installed like any other googleapis/gax-php dependencies in Composer, but it is used at runtime only if the C implementation is not installed and configured.

C implementation

To install and configure the Protobuf PHP extension:

Run sudo pecl install protobuf from the command line.
Add an extension=protobuf.so line to the php.ini file.

PHP implementation

Make sure the C implementation is disabled and all the dependencies of the googleapis/gax-php library are installed:

Comment out any extension=protobuf.so line in php.ini.
Run composer install from the directory that contains the composer.json file of the project being worked on. The composer.json should specify google-ads-php or any project that requires it as a dependence.

Key Point: Typically, the protobuf version that this PHP library relies on is transitively specified in composer.json of google/gax, which is one of the core dependencies. But for performance or compatibility reasons, we may specify the protobuf version directly in the PHP library's composer.json.

Determine which implementation is being used

Run php -i | grep protobuf:

If not empty, you're using the C implementation.
Otherwise, you're not using the C implementation and the Google Ads API PHP library will rely on the PHP implementation (if installed correctly using Composer).