Protobuf for PHP is an implementation of Google's Protocol Buffers for the PHP
language, supporting its binary data serialization and including a protoc
plugin to generate PHP classes from .proto files.
Great effort has been put into generating PHP files that include all sort of type hints to aide IDE's with autocompletion. Therefore, it can not only be used to communicate with Protocol Buffers services but also as a generation tool for data objects no matter what the final serialization is.
For more information see the included man pages.
protoc compiler version 2.3 or aboveGMP or BC Math extensions ¹
¹ Only needed for negative values in int32, int64 or fixed64 types. See
the known issues section.
¹ Only serialization is supported in this codec
$person = new Tutorial\Person();
$person->name = 'DrSlump';
$person->setId(12);
$book = new Tutorial\AddressBook();
$book->addPerson($person);
// Use default codec
$data = $book->serialize();
// Use custom codec
$codec = new \DrSlump\Protobuf\Codec\Json();
$data = $codec->encode($book);
// ... or ...
$data = $book->serialize($codec);composer installPHP is very weak when dealing with numbers processing. Several work arounds have been applied to the standard binary codec to reduce incompatibilities between Protobuf types and PHP ones.
Protobuf stores floating point values using the IEEE 754 standard
with 64bit words for the double and 32bit for the float types. PHP supports IEEE 754 natively although
the precission is platform dependant, however it typically supports 64bit doubles. It means that
if your PHP was compiled with 64bit sized doubles (or greater) you shouldn't have any problem encoding
and decoded float and double typed values with Protobuf.
Integer values are also platform dependant in PHP.
The library has been developed and tested against PHP binaries compiled with 64bit integers. The encoding and
decoding algorithm should in theory work no matter if PHP uses 32bit or 64bit integers internally, just take
into account that with 32bit integers the numbers cannot exceed in any case the PHP_INT_MAX value (2147483647).
While Protobuf supports unsigned integers PHP does not. In fact, numbers above the compiled PHP maximum
integer (PHP_INT_MAX, 0x7FFFFFFFFFFFFFFF for 64bits) will be automatically casted to doubles, which
typically will offer 53bits of decimal precission, allowing to safely work with numbers upto
0x20000000000000 (2^53), even if they are represented in PHP as floats instead of integers. Higher numbers
will loose precission or might even return an infinity value, note that the library does not include
any checking for these numbers and using them might provoke unexpected behaviour.
Negative values when encoded as int32, int64 or fixed64 types require the big integer extensions
GMP or BC Math (the later only for 64bit architectures)
to be available in your PHP environment. The reason is that when encoding these negative numbers without
using zigzag the binary representation uses the most significant bit for the sign, thus the numbers become
above the maximum supported values in PHP. The library will check for these conditions and will automatically
try to use GMP or BC to process the value.
The binary codec expects strings to be encoded using UTF-8. PHP does not natively support string encodings,
PHP's string data type is basically a length delimited stream of bytes, so it's not trivial to include
automatic encoding conversion into the library encoding and decoding routines. Instead of trying to guess
or offer a configuration interface for the encoding, the binary codec will process the string type just as
it would process byte one, delegating on your application the task of encoding or decoding in the desired
character set.
Large messages might be troublesome since the way the library is modelled does not allow to parse or serialize messages as streams, instead the whole operation is performed in memory, which allows for faster processing but could consume too much RAM if messages are too large.
Since wire types are different across different codec's formats, it's not possible to transcode unkwnon fields consumed in one codec to another. This means, for example, that when consuming a message using the binary codec, if it contains unknown fields they won't be included when serializing the message using the Json codec.
The generation tool is designed to be run as a protoc plugin, thus it should
work with any proto file supported by the official compiler.
protoc --plugin=protoc-gen-php --php_out=./build tutorial.protoTo make use of non-standard options in your proto files (like php.namespace) you'll
have to import the php.proto file included with the library. It's location will
depend on where you've installed this library.
protoc -I=./Protobuf-PHP/library/DrSlump/Protobuf/Compiler/protos \
--plugin=protoc-gen-php --php_out=./build tutorial.protoIn order to make your life easier, the supplied protoc plugin offers an additional
execution mode, where it acts as a wrapper for the protoc invocation. It will
automatically include the php.proto path so you don't need to worry about it.
protoc-gen-php -o ./build tutorial.protomkdir -p test/generated ./protoc-gen-php.php -o test/generated -Dmultifile=true -i ./test/library/DrSlump/Protobuf/Test/protos/ ./test/library/DrSlump/Protobuf/Test/protos/*.proto ./vendor/bin/phpunit