20. Application Exercise – Version 10
The previous version showed that tax data, shared by all users of the application, should be stored in an [Application]-scope cache. We will use a Redis server [https://redis.io] to implement this.
20.1. Redis
The [Application] scope memory will be implemented by a Redis server. The PHP scripts that need this application memory will be clients of this server:
20.2. Installing Redis
Laragon comes with a Redis server that is not enabled by default. You must therefore start by enabling it:
- In [3], enable the [Redis] server;
- In [4], leave port [6379] as the default used by Redis clients;
Laragon services are automatically restarted after Redis is enabled:
20.3. The Redis client in command mode
The Redis server can be queried in command mode. Open a Laragon terminal (see link section):
- In [1], the [redis-cli] command launches the client in command mode for the Redis server;
As of July 2019, the Redis client supports 172 commands for interacting with the server [https://redis.io/commands#list]. One of them [command count] [2] displays this number [3].
We will only cover the ones we need for our PHP application. We will use Redis for a single purpose: storing an array [‘attribute’=>’value’] in Redis memory. This is done with the Redis command [set attribute value] [4]. The value can then be retrieved using the [get attribute] command [5]. That’s all we’ll need.
It may be necessary to clear Redis’s memory. This is done with the [flushdb] command [6]. Then, if we query the value of the [title] attribute [7], we get a [nil] reference [8] indicating that the attribute was not found. We can also use the [exists] command [9-10] to check if an attribute exists.
To exit the Redis client, type the [quit] command [11].
20.4. Installing a Redis Client for PHP
We now need to install a Redis client for PHP:
There are several libraries that implement a Redis client. We will use the [Predis] library [https://github.com/nrk/predis] (July 2019). Like the previous ones, this one is installed with [composer] in a Laragon terminal:
20.5. Server code
The configuration file [config-server.json] changes as follows:
{
"rootDirectory": "C:/myprograms/laragon-lite/www/php7/scripts-web/impots/version-10",
"databaseFilename": "Data/database.json",
"relativeDependencies": [
"/../version-08/Entities/BaseEntity.php",
"/../version-08/Entities/ExceptionImpots.php",
"/../version-08/Entities/TaxAdminData.php",
"/../version-08/Entities/Database.php",
"/../version-08/Dao/InterfaceServerDao.php",
"/../version-08/Dao/ServerDao.php",
"/../version-09/Dao/ServerDaoWithSession.php",
"/../version-08/Métier/InterfaceServerMetier.php",
"/../version-08/Métier/ServerMetier.php",
"/../version-09/Utilities/Logger.php",
"/../version-09/Utilities/SendAdminMail.php"
],
"absoluteDependencies": [
"C:/myprograms/laragon-lite/www/vendor/autoload.php",
"C:/myprograms/laragon-lite/www/vendor/predis/predis/autoload.php"
],
"users": [
{
"login": "admin",
"passwd": "admin"
}
],
"adminMail": {
"smtp-server": "localhost",
"smtp-port": "25",
"from": "guest@localhost",
"to": "guest@localhost",
"subject": "plantage du serveur de calcul d'impôts",
"tls": "FALSE",
"attachments": []
},
"logsFilename": "Data/logs.txt"
}
Comments
- lines 5–15: Version 10 does not introduce anything new apart from the [impots-server.php] script. It uses elements from versions 08 and 09;
- line 19: a dependency required for the [predis] library that we just installed;
The server code [impots-server.php] changes as follows:
<?php
// strict adherence to declared types of function parameters
declare (strict_types=1);
// namespace
namespace Application;
// error handling by PHP
ini_set("display_errors", "0");
//
// configuration file path
define("CONFIG_FILENAME", "Data/config-server.json");
// class alias
use \Application\ServerDaoWithSession as ServerDaoWithRedis;
// session
$session = new Session();
$session->start();
…
…
// 1st log
$logger->write("\n---nouvelle requête\n");
// retrieve the current query
$request = Request::createFromGlobals();
// authentication only the 1st time
if (!$session->has("user")) {
…
} else {
// log
$logger->write("Authentification prise en session…\n");
}
// we have a valid user - we check the parameters received
$erreurs = [];
// you need three parameters GET
$method = strtolower($request->getMethod());
…
// mistakes?
if ($erreurs) {
// an error code 400 HTTP_BAD_REQUEST is sent to the customer
sendResponse($response, ["erreurs" => $erreurs], Response::HTTP_BAD_REQUEST, [], $logger);
// completed
exit;
} else {
// logs
$logger->write("paramètres ['marié'=>$marié, 'enfants'=>$enfants, 'salaire'=>$salaire] valides\n");
}
// we've got everything you need to work
// Redis
\Predis\Autoloader::register();
try {
// customer [predis]
$redis = new \Predis\Client();
// connect to the server to see if it's there
$redis->connect();
} catch (\Predis\Connection\ConnectionException $ex) {
// internal server error
doInternalServerError("[redis], " . utf8_encode($ex->getMessage()), $response, $config['adminMail'], $logger);
// completed
exit;
}
// creation of the [dao] layer
if (!$redis->get("taxAdminData")) {
// tax data is taken from the database
$logger->write("données fiscales prises en base de données\n");
try {
// construction of the [dao] layer
$dao = new ServerDaoWithRedis($config["databaseFilename"], NULL);
// put tax data in scope memory [application]
// method [TaxAdminData]->__toString will be called implicitly
$redis->set("taxAdminData", $dao->getTaxAdminData());
} catch (\RuntimeException $ex) {
// we note the error
doInternalServerError("[dao], " . utf8_encode($ex->getMessage()), $response, $config['adminMail'], $logger, $redis);
// completed
exit;
}
} else {
// tax data are taken from the [application] scope memory
$arrayOfAttributes = \json_decode($redis->get("taxAdminData"), true);
$taxAdminData = (new TaxAdminData())->setFromArrayOfAttributes($arrayOfAttributes);
// istanciation of the [dao] layer
$dao = new ServerDaoWithRedis(NULL, $taxAdminData);
// logs
$logger->write("données fiscales prises dans redis\n");
}
// creation of the [business] layer
$métier = new ServerMetier($dao);
// tAX CALCULATION
$result = $métier->calculerImpot($marié, (int) $enfants, (int) $salaire);
// we return the answer
sendResponse($response, $result, Response::HTTP_OK, [], $logger, $redis);
// end
exit;
function doInternalServerError(string $message, Response $response, array $infos,
Logger $logger = NULL, \Predis\Client $predisClient = NULL) {
// $message: error message
// $response : answer HTTP
// $infos: information table for sending mail
// $result: results table
// $logger: application logger
// $predisClient: a customer [predis]
//
// send an e-mail to the administrator
// SendAdminMail intercepts all exceptions and logs them itself
$infos['message'] = $message;
$sendAdminMail = new SendAdminMail($infos, $logger);
$sendAdminMail->send();
// an error code 500 is sent to the customer
sendResponse($response, ["erreur" => $message], Response::HTTP_INTERNAL_SERVER_ERROR, [], $logger, $predisClient);
}
// function to send HTTP response to client
function sendResponse(Response $response, array $result, int $statusCode,
array $headers, Logger $logger = NULL, \Predis\Client $predisClient = NULL) {
// $response : answer HTTP
// $result: results table
// $statusCode: HTTP response status
// $headers: HTTP headers to be included in the response
// $logger: application logger
// $predisClient: a customer [predis]
//
// status HTTTP
$response->setStatusCode($statusCode);
// body
$body = \json_encode(["réponse" => $result], JSON_UNESCAPED_UNICODE);
$response->setContent($body);
// headers
$response->headers->add($headers);
// shipping
$response->send();
// log
if ($logger != NULL) {
$logger->write("$body\n");
$logger->close();
}
// close connection [redis]
if ($predisClient != NULL) {
$predisClient->disconnect();
}
}
Comments
- line 15: we give the alias [ServerDaoWithRedis] to the class [\Application\ServerDaoWithSession] to reflect the change in the server script’s implementation;
- lines 18–19: the session is maintained. Here, we need to keep two pieces of information in mind:
- the fact that the user has authenticated successfully. This information has [session] scope: it is tied to a specific user and is not valid for other users;
- the tax administration data. This information has [application] scope: it is not linked to a specific user but applies to all users;
- lines 54–64: creation of the [redis] client that will communicate with the [redis] server. This client will communicate with the server’s default port. If the server were not communicating on its default port or if it were not on the [localhost] machine, this information would need to be passed to the constructor of the [\Predis\Client] class;
- line 59: the client is immediately connected to the server to check if it responds;
- lines 60–65: if the connection to the Redis server fails, an error response is sent to the client and an email is sent to the application administrator;
- line 67: we query the [redis] server for the key [taxAdminData]. If it is not found, then the tax data is retrieved from the database (line 72);
- line 75: the key [taxAdminData] is stored in [redis] memory along with the JSON string of the variable [$taxAdminData], which is an object of type [TaxAdminData]. The [$redis→set] method expects a string for the key’s value. It will therefore attempt to convert the [TaxAdminData] object to a [string] type. This implicitly calls the [TaxAdminData->__toString] method, which produces the JSON string of the [TaxAdminData] object;
- line 84: the key [taxAdminData] is in the [redis] memory, so we retrieve its value. We know this is the JSON string of a [TaxAdminData] object. We then parse this to obtain an array of attributes;
- line 85: from this array, a new [TaxAdminData] object is instantiated;
- line 87: the [dao] layer is instantiated;
20.6. Client code
Client version 10 is identical to version 9. The only change is to the configuration file [config-client.json]:
{
"rootDirectory": "C:/Data/st-2019/dev/php7/poly/scripts-console/impots/version-10",
"taxPayersDataFileName": "Data/taxpayersdata.json",
"resultsFileName": "Data/results.json",
"errorsFileName": "Data/errors.json",
"dependencies": [
"/../version-08/Entities/BaseEntity.php",
"/../version-08/Entities/TaxPayerData.php",
"/../version-08/Entities/ExceptionImpots.php",
"/../version-08/Utilities/Utilitaires.php",
"/../version-08/Dao/InterfaceClientDao.php",
"/../version-08/Dao/TraitDao.php",
"/../version-09/Dao/ClientDao.php",
"/../version-08/Métier/InterfaceClientMetier.php",
"/../version-08/Métier/ClientMetier.php"
],
"absoluteDependencies": [
"C:/myprograms/laragon-lite/www/vendor/autoload.php"
],
"user": {
"login": "admin",
"passwd": "admin"
},
"urlServer": "https://localhost:443/php7/scripts-web/impots/version-10/impots-server.php"
}
The only change is the server URL on line 24.
The results are the same as in version 09. Let’s just test a new error case:
The result in the console is as follows:
L'erreur suivante s'est produite : {"statut HTTP":500,"erreur":"[redis], Aucune connexion n’a pu être établie car l’ordinateur cible l’a expressément refusée. [tcp:\/\/127.0.0.1:6379]"}
Terminé
20.7. [Codeception] client tests
The [ClientMetierTest] test class in version 10 is identical to that in version 09 with one exception:
<?php
// strict adherence to declared types of function parameters
declare (strict_types=1);
// namespace
namespace Application;
// definition of constants
define("ROOT", "C:/Data/st-2019/dev/php7/poly/scripts-console/impots/version-10");
…
}
- line 10: the test environment is that of the version 10 client;
Before starting the tests, let’s use the [redis-cli] client to delete the [taxAdminData] key from the [redis] server’s memory:
Now, let’s run the test:
Now let’s examine the server logs [logs.txt]:
05/07/19 08:52:16:396 :
---nouvelle requête
05/07/19 08:52:16:403 : Autentification en cours…
05/07/19 08:52:16:403 : Authentification réussie [admin, admin]
05/07/19 08:52:16:403 : paramètres ['marié'=>oui, 'enfants'=>2, 'salaire'=>55555] valides
05/07/19 08:52:16:407 : données fiscales prises en base de données
05/07/19 08:52:16:420 : {"réponse":{"impôt":2814,"surcôte":0,"décôte":0,"réduction":0,"taux":0.14}}
05/07/19 08:52:16:546 :
---nouvelle requête
05/07/19 08:52:16:555 : Autentification en cours…
05/07/19 08:52:16:555 : Authentification réussie [admin, admin]
05/07/19 08:52:16:556 : paramètres ['marié'=>oui, 'enfants'=>2, 'salaire'=>50000] valides
05/07/19 08:52:16:559 : données fiscales prises dans redis
05/07/19 08:52:16:559 : {"réponse":{"impôt":1384,"surcôte":0,"décôte":384,"réduction":347,"taux":0.14}}
05/07/19 08:52:16:668 :
---nouvelle requête
05/07/19 08:52:16:675 : Autentification en cours…
05/07/19 08:52:16:675 : Authentification réussie [admin, admin]
05/07/19 08:52:16:675 : paramètres ['marié'=>oui, 'enfants'=>3, 'salaire'=>50000] valides
05/07/19 08:52:16:678 : données fiscales prises dans redis
05/07/19 08:52:16:678 : {"réponse":{"impôt":0,"surcôte":0,"décôte":720,"réduction":0,"taux":0.14}}
05/07/19 08:52:16:776 :
---nouvelle requête
…
We have already mentioned that for each test, the test class constructor is re-executed, which means that the [ClientDao] class being tested is instantiated with a non-existent session cookie for each test. Everything therefore proceeds as if the 11 tests represented 11 different users, with 11 different sessions.
- line 6: tax data is retrieved from the database;
- lines 13, 20: tax data is retrieved from the [Redis] memory. We therefore have an [application] scope memory shared by all users of the application;
20.8. [Redis] Server Web Interface
We have seen that the [Redis] server can be managed in command mode. It can also be managed via a web interface:
- in [4], the administration URL;
- in [5], the keys stored by the server;
- in [6], the current server status;
By clicking on [5], you can view information about the [taxAdminData] key:
- in [7], the URL that provides access to the information for the [taxAdminData] key [8];
- in [9], the key’s status;
- in [10], its value: you can recognize the JSON string of a [TaxAdminData] object;
- In [11], you can delete the key;
- in [12], you can add another one;