(PHP Extension) Firebase Receive Server-Sent Events (text/event-stream)

Demonstrates how to start receiving server-sent events and update your JSON database with each event.

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<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

// Demonstrates how to begin receiving server-sent events, and to update
// your JSON database for each event.

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// This example assumes a JWT authentication token, if required, has been previously obtained.
// See Get Firebase Access Token from JSON Service Account Private Key for sample code.

// Load the previously obtained Firebase access token into a string.
$fac = new CkFileAccess();
$accessToken = $fac->readEntireTextFile('qa_data/tokens/firebaseToken.txt','utf-8');
if ($fac->get_LastMethodSuccess() != true) {
    print $fac->lastErrorText() . "\n";
    exit;
}

$rest = new CkRest();

// Make the initial connection (without sending a request yet).
// Once connected, any number of requests may be sent.  It is not necessary to explicitly
// call Connect before each request.  
$success = $rest->Connect('chilkat.firebaseio.com',443,true,true);
if ($success != true) {
    print $rest->lastErrorText() . "\n";
    exit;
}

$authGoogle = new CkAuthGoogle();
$authGoogle->put_AccessToken($accessToken);
$rest->SetAuthGoogle($authGoogle);

$rest->AddHeader('Accept','text/event-stream');
$rest->AddHeader('Cache-Control','no-cache');

$responseBody = $rest->fullRequestNoBody('GET','/.json');

// A 307 redirect response is expected.
if ($rest->get_ResponseStatusCode() != 307) {
    print 'Unexpected response code: ' . $rest->get_ResponseStatusCode() . "\n";
    print $responseBody . "\n";
    print 'Failed.' . "\n";
    exit;
}

// Get the redirect URL
// url is a CkUrl
$url = $rest->RedirectUrl();
if ($rest->get_LastMethodSuccess() != true) {
    print $rest->lastErrorText() . "\n";
    exit;
}

print 'redirect URL domain: ' . $url->host() . "\n";
print 'redirect URL path: ' . $url->path() . "\n";
print 'redirect URL query params: ' . $url->query() . "\n";
print 'redirect URL path with query params: ' . $url->pathWithQueryParams() . "\n";

// Our text/event-stream will be obtained from the redirect URL...
$rest2 = new CkRest();

$success = $rest2->Connect($url->host(),443,true,true);
if ($success != true) {
    print $rest2->lastErrorText() . "\n";

    exit;
}

$rest2->AddHeader('Accept','text/event-stream');
$rest2->AddHeader('Cache-Control','no-cache');

// Add the redirect query params to the request
$rest2->AddQueryParams($url->query());

// In our case, we don't actually need the auth query param,
// so remove it.
$rest2->RemoveQueryParam('auth');

// Send the request.  (We are only sending the request here.
// We are not yet getting the response because the response
// will be a text/event-stream.)
$success = $rest2->SendReqNoBody('GET',$url->path());
if ($success != true) {
    print $rest2->lastErrorText() . "\n";

    exit;
}

// Read the response header.  
// We want to first get the response header to see if it's a successful
// response status code.  If not, then the response will not be a text/event-stream
// and we should read the response body normally.
$responseStatusCode = $rest2->ReadResponseHeader();
if ($responseStatusCode < 0) {
    print $rest2->lastErrorText() . "\n";
    exit;
}

// If successful, a 200 response code is expected.
// If the reponse code is not 200, then read the response body and fail..
if ($responseStatusCode != 200) {
    print 'Response Code: ' . $responseStatusCode . "\n";
    print 'Response Status Text: ' . $rest2->responseStatusText() . "\n";
    print 'Response Header: ' . $rest2->responseHeader() . "\n";
    $responseBody = $rest2->readRespBodyString();
    if ($rest2->get_LastMethodSuccess() == true) {
        print 'Error Response Body: ' . $responseBody . "\n";
    }

    print 'Failed.' . "\n";
    exit;
}

// For this example, our JSON database will be empty at the beginning.
// The incoming events (put and patch) will be applied to this database.
$jsonDb = new CkJsonObject();

// Make sure to set the JSON path delimiter to "/".  The default is "." and this
// is not compatible with Firebase paths.
$jsonDb->put_DelimiterChar('/');

// At this point, we've received the response header.  Now it's time to begin
// receiving the event stream.  We'll start a background thread to read the 
// stream.  (Our main application (foreground) thread can cancel it at any time.)  
// While receiving in the background thread, our foreground thread can read the stream
// as it desires..
$eventStream = new CkStream();

// This sse object will be used as a helper to parse the server-sent event stream.
$sse = new CkServerSentEvent();

// task is a CkTask
$task = $rest2->ReadRespBodyStreamAsync($eventStream,true);
$task->Run();

// For this example, we'll just read a few events, and then cancel the
// async task.
$count = 0;
while (($count < 3) and ($task->get_Finished() == false)) {

    // Get the next event, which is a series of text lines ending with
    // a blank line. 
    // Note: This method blocks the calling thread until a message arrives.
    // a program might instead periodically check the availability of
    // data via the stream's DataAvailable property, and then do the read.

    // An alternative to writing a while loop to read the event stream
    // would be to setup some sort of timer event in your program (using whatever timer functionality
    // is provided in a programming language/environment), to periodically check the eventStream's
    // DataAvailable property and consume the incoming event.
    $eventStr = $eventStream->readUntilMatch('\r\n\r\n');
    if ($eventStream->get_LastMethodSuccess() != true) {
        print $eventStream->lastErrorText() . "\n";
        // Force the loop to exit by setting the count to a high number.
        $count = 99999;
    }
    else {
        print 'Event: [' . $eventStr . ']' . "\n";

        // We have an event. Let's update our local copy of the JSON database.
        $success = $sse->LoadEvent($eventStr);
        if ($success != true) {
            print 'Failed to load sse event: ' . $eventStr . "\n";
        }
        else {
            // Now we can easily access the event name and data, and apply it to our JSON database:
            $success = $jsonDb->FirebaseApplyEvent($sse->eventName(),$sse->data());
            if ($success != true) {
                print 'Failed to apply event: ' . $sse->eventName() . ': ' . $sse->data() . "\n";
            }
            else {
                print 'Successfully applied event: ' . $sse->eventName() . ': ' . $sse->data() . "\n";
            }

        }

    }

    $count = $count + 1;
}

// Make sure the background task is cancelled if still running.
$task->Cancel();

// Examine the JSON database after applying events..
$jsonDb->put_EmitCompact(false);
print '----' . "\n";
print $jsonDb->emit() . "\n";

?>