PHP Protobuf - Google's Protocol Buffers for PHP
, (*1)
Protocol Buffers are a way of encoding structured data in an efficient yet extensible format. It might be used in file formats and RPC protocols., (*2)
PHP Protobuf is Google's Protocol Buffers implementation for PHP with a goal to provide high performance, including a protoc plugin to generate PHP classes from .proto files. The heavy-lifting (a parsing and a serialization) is done by a PHP extension., (*3)
- Installation
- Documentation
- Contributing
- Roadmap
- License and Authors
- References
Installation
Dependencies
- PHP 5.4 or above
- Protobuf
protoc compiler 2.6 or above
- Protobuf message version
proto2
Composer Install
Install From Source
- Clone the source code
git clone https://github.com/allegro/php-protobuf
- Go to the source code directory
cd php-protobuf
- Build and install the PHP extension (follow instructions at [php.net][2])
- Install protoc plugin dependencies
composer install
Documentation
-
Assume you have a file foo.proto, (*4)
message Foo
{
required int32 bar = 1;
optional string baz = 2;
repeated float spam = 3;
}
-
Compile foo.proto, (*5)
php protoc-gen-php.php foo.proto
-
Create Foo message and populate it with some data, (*6)
require_once 'Foo.php';
$foo = new Foo();
$foo->setBar(1);
$foo->setBaz('two');
$foo->appendSpam(3.0);
$foo->appendSpam(4.0);
-
Serialize a message to a string, (*7)
$packed = $foo->serializeToString();
-
Parse a message from a string, (*8)
$parsedFoo = new Foo();
try {
$parsedFoo->parseFromString($packed);
} catch (Exception $ex) {
die('Oops.. there is a bug in this example, ' . $ex->getMessage());
}
-
Let's see what we parsed out, (*9)
$parsedFoo->dump();
It should produce output similar to the following:, (*10)
Foo {
1: bar => 1
2: baz => 'two'
3: spam(2) =>
[0] => 3
[1] => 4
}
-
If you would like you can reset an object to its initial state, (*11)
$parsedFoo->reset();
Compilation
Use protoc-php.php script to compile your proto files. It requires extension to be installed., (*12)
php protoc-php.php foo.proto
Specify --use-namespaces or -n option to generate classes using native PHP namespaces., (*13)
php protoc-php.php -n foo.proto
Package
If a proto file is compiled with a -n / --use-namespaces option a package is represented as an namespace. Otherwise message and enum name is prefixed with it separated by underscore. The package name is composed of a respective first-upper-case parts separated by underscore., (*14)
Message and enum name
- underscore separated name is converted to CamelCased
- embedded name is composed of parent message name separated by underscore
Message interface
PHP Protobuf module implements ProtobufMessage class which encapsulates protocol logic. Message compiled from proto file extends this class providing message field descriptors. Based on these descriptors ProtobufMessage knows how to parse and serialize messages of the given type., (*15)
For each field a set of accessors is generated. Methods actually accessible are different for single value fields (required / optional) and multi-value fields (repeated)., (*16)
-
required / optional, (*17)
get{FIELD}() // return field value
set{FIELD}($value) // set field value to $value
-
repeated, (*18)
append{FIELD}($value) // append $value value to field
clear{FIELD}() // empty field
get{FIELD}() // return array of field values
getAt{FIELD}($index) // return field value at $index index
getCount{FIELD}() // return number of field values
getIterator{FIELD}($index) // return ArrayIterator for field values
{FIELD} is camel cased field name., (*19)
Enums
PHP does not natively support enum type. Hence enum is compiled to a class with set of constants., (*20)
Enum field is simple PHP integer type., (*21)
Type mapping
Range of available build-in PHP types poses some limitations. PHP does not support 64-bit positive integer type. Note that parsing big integer values might result in getting unexpected results., (*22)
Protocol Buffers types map to PHP types as follows:, (*23)
| Protocol Buffers | PHP |
| ---------------- | ------ |
| double | float |
| float | |
| ---------------- | ------ |
| int32 | int |
| int64 | |
| uint32 | |
| uint64 | |
| sint32 | |
| sint64 | |
| fixed32 | |
| fixed64 | |
| sfixed32 | |
| sfixed64 | |
| ---------------- | ------ |
| bool | bool |
| ---------------- | ------ |
| string | string |
| bytes | |
Not set value is represented by null type. To unset value just set its value to null., (*24)
Parsing
To parse message create message class instance and call its parseFromString method passing it prior to the serialized message. Errors encountered are signaled by throwing Exception. Exception message provides detailed explanation. Required fields not set are silently ignored., (*25)
$packed = /* serialized FooMessage */;
$foo = new FooMessage();
try {
$foo->parseFromString($packed);
} catch (Exception $ex) {
die('Parse error: ' . $e->getMessage());
}
$foo->dump(); // see what you got
Serialization
To serialize message call serializeToString method. It returns a string containing protobuf-encoded message. Errors encountered are signaled by throwing Exception. Exception message provides detailed explanation. Required field not set triggers an error., (*26)
$foo = new FooMessage()
$foo->setBar(1);
try {
$packed = $foo->serializeToString();
} catch (Exception $ex) {
die 'Serialize error: ' . $e->getMessage();
}
/* do some cool stuff with protobuf-encoded $packed */
Dumping
There might be situations you need to investigate what actual content of the given message is. What var_dump gives on message instance is somewhat obscure., (*27)
ProtobufMessage class comes with dump method which prints out a message content to the standard output. It takes one optional argument specifying whether you want to dump only set fields. By default it dumps only set fields. Pass false as argument to dump all fields. Format it produces is similar to var_dump., (*28)
Example
-
foo.proto, (*29)
message Foo
{
required int32 bar = 1;
optional string baz = 2;
repeated float spam = 3;
}
-
pb_proto_foo.php, (*30)
php protoc-php.php foo.proto
-
foo.php, (*31)
<?php
require_once 'pb_proto_foo.php';
$foo = new Foo();
$foo->setBar(1);
$foo->setBaz('two');
$foo->appendSpam(3.0);
$foo->appendSpam(4.0);
$packed = $foo->serializeToString();
$foo->clear();
try {
$foo->parseFromString($packed);
} catch (Exception $ex) {
die('Oops.. there is a bug in this example');
}
$foo->dump();
?>
php foo.php should produce following output:, (*32)
Foo {
1: bar => 1
2: baz => 'two'
3: spam(2) =>
[0] => 3
[1] => 4
}
License and Authors
- Author: Hubert JagodziĆski (https://github.com/hjagodzinski)
- Author: Mateusz Gajewski (https://github.com/wendigo)
- Author: Sergey P (https://github.com/serggp)
- Author: Christopher Mancini (https://github.com/christophermancini)
Copyright (c) 2017 Allegro Group (Original Authors)
Copyright (c) 2017 Basho Technologies, Inc., (*33)
Licensed under the Apache License, Version 2.0 (the "License"). For more details, see License., (*34)
References
Wallogit.com
