Integration of PHP and data flow processing

With the continuous upgrading of data processing requirements and the popularization of big data applications, data stream processing technology has been widely used in recent years. The purpose of data stream processing technology is to process data in real time in the data stream and to generate new data stream results simultaneously during the processing process. PHP is a very popular web programming language that supports data processing, and after PHP7.0 version, it has introduced some new features to meet the needs of data flow processing, such as Generator, Closure, Type Hints, etc. This article will introduce how PHP is integrated with data stream processing technology.

1. What is data stream processing?

In short, data flow processing is a technology for processing data streams. It is a way of processing data in real time. Unlike batch processing, it can process continuous data from multiple sources. . The processing results of data flow processing can be sent directly to downstream processing nodes or persisted to storage devices.

2. How does PHP implement data stream processing?

In previous versions, PHP could not directly operate stream data, and developers could only operate through libraries in other languages. But after PHP7.0 version, PHP introduced Generator, Closure and other features, enabling PHP to support data stream processing.

1. Generator

Generator is one of the new features of PHP. It can provide a more flexible method to generate iterators. The Generator function can combine processing logic and iterator functions. Generate a data stream. Consider the following example:

function dataGenerator($n){
    for($i=0;$i<$n;$i++){
        yield $i;
    }
}

$data = dataGenerator(10);
foreach($data as $entry){
    echo $entry.PHP_EOL;
}

Through the above code, we can see that the sequence of data points generated by the dataGenerator function can be processed as a data stream. The advantage of using the Generator function to operate data streams is that it can optimize memory usage and reduce memory overhead when processing data sets.

2. Closure

Closure is another new feature of PHP. It is an anonymous function that can capture variables defined in the external scope, and then during the actual execution process, Use these variables. Closure is usually used together with Generator to process data streams.

Consider the following example:

$data = [1, 2, 3, 4];

$mapper = function($value){
    return $value * $value;
};

$closure = function($data,$mapper){
    foreach($data as $entry) {
        yield $mapper($entry);
    }
};

$stream = $closure($data,$mapper);
foreach($stream as $entry){
    echo $entry.PHP_EOL;
}

The above code uses Closure to implement a data flow, square the value in the data source $data and return it. Closure provides a powerful mechanism to treat a function as an object and facilitate passing it between data streams.

3. Data stream processing framework

Although PHP7.0 can already support data stream processing, in order to process data streams more easily, you can use a third-party data stream processing framework. Below we will introduce two classic data flow processing frameworks in PHP.

1. ReactPHP

ReactPHP is an event-driven programming framework that can be used to build high-performance asynchronous applications and supports web applications, HTTP servers and Socket servers. ReactPHP is based on a single-threaded event loop model, processing multiple parallel requests and generating streaming data by responding to events.

The code for using ReactPHP to implement data stream processing is as follows:

$stream = new ReactStreamReadableResourceStream(
    fopen(__DIR__ . '/../fixture/lorem-ipsum.txt', 'r'),
    $loop
);

$stream->on('data', function($data) use ($output) {
    $output->write($data);
    echo $data;
});

In the above code, we use ReactPHP's event loop mechanism to create a data stream. In the event loop, $stream reads data and continuously triggers callback functions to process data inflow.

2. Fractal

Fractal is a library that implements data flow processing in PHP. This library is mainly used to format and convert data. We can use Fractal to create data in multiple hierarchies. flow.

Fractal is often used to handle the following two situations that require greater support for data stream processing:

(1) When you want to build a specific response format step by step, Fractal can handle the lack of Save code, however which grouped data or attributes will be very different;

(2) When your data layers are on different physical addresses, merging these data streams has higher concurrency Performance, in this way, multiple data streams can be processed with complexity and flexibility.

Example:

$books = [
    [
        "id" => 1,
        "title" => 'A Game of Thrones',
        "author_name" => 'George R. R. Martin',
        "currency" => 'USD',
        "price" => 19.99
    ]
];
$manager = new LeagueFractalManager();
$resource = new LeagueFractalResourceCollection($books, function ($book) {
    return [
        'id' => (int) $book['id'],
        'title' => $book['title'],
        'author' => [
            "name" => $book['author_name'],
        ],
        'price' => [
            'currency' => $book['currency'],
            'amount' => $book['price']
        ]
    ];
});

$manager->setSerializer(new LeagueFractalSerializerJsonApiSerializer());
$json = $manager->createData($resource)->toJson();
echo $json.PHP_EOL;

In the above code, we use Fractal's Manager and Collection to implement data flow processing. Manager is used to handle the serialization details of the data, and Collection is used to build the transmission format. Here, we use JsonApiSerializer as a serialization tool to generate a data stream in JSON format.

4. Conclusion

The innovation and popularization of data flow technology is of great significance to the further development of the field of data processing in the future. This article mainly introduces the method of using data flow processing technology in PHP, including the new features of PHP7.0, the use of Closure and Generator, and the practical application of data flow processing frameworks such as Fractal and ReactPHP. With the continuous advancement of big data applications, it is believed that data stream processing technology will be more widely used in the future.

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