Add persistent session support with automatic token renewal and retry

composer.json

@@ -18,6 +18,9 @@
     "phpunit/phpunit": "*",
     "phpstan/phpstan": "^2.0"
   },
+  "suggest": {
+    "ext-apcu": "Optional: required only by the built-in ApcuSessionCache backend."
+  },
   "autoload": {
     "psr-4": {
       "INTERMediator\\FileMakerServer\\RESTAPI\\": "src/"

src/FMDataAPI.php

@@ -2,6 +2,7 @@
 
 namespace INTERMediator\FileMakerServer\RESTAPI;
 
+use INTERMediator\FileMakerServer\RESTAPI\SessionCache\SessionCacheInterface;
 use INTERMediator\FileMakerServer\RESTAPI\Supporting\FileMakerLayout;
 use INTERMediator\FileMakerServer\RESTAPI\Supporting\FileMakerRelation;
 use INTERMediator\FileMakerServer\RESTAPI\Supporting\CommunicationProvider;
@@ -58,23 +59,33 @@
      * Ex.  [{"database"=>"<databaseName>", "username"=>"<username>", "password"=>"<password>"}].
      * If you use OAuth, "oAuthRequestId" and "oAuthIdentifier" keys have to be specified.
      * @param boolean $isUnitTest If it's set to true, the communication provider just works locally.
-     */
-    public function __construct(string      $solution,
-                                string      $user,
-                                string|null $password,
-                                string|null $host = null,
-                                int|null    $port = null,
-                                string|null $protocol = null,
-                                array|null  $fmDataSource = null,
-                                bool        $isUnitTest = false)
+     * @param SessionCacheInterface|null $sessionCache Cache backend for persistent sessions.
+     * If omitted, the library logs in and out on every database operation, or once
+     * per communication scope when using startCommunication() / endCommunication().
+     * If specified, session tokens are persisted and reused across requests via
+     * startCommunication() / endCommunication(), avoiding redundant logins against the FileMaker Server.
+     * When a session cache is specified, {@see self::setRetryOnAccessTokenInvalidation()} is
+     * automatically set to true, ensuring the library re-authenticates and retries the request if
+     * the cached token has expired on the FileMaker Server.
+     */
+    public function __construct(string                     $solution,
+                                string                     $user,
+                                string|null                $password,
+                                string|null                $host = null,
+                                int|null                   $port = null,
+                                string|null                $protocol = null,
+                                array|null                 $fmDataSource = null,
+                                bool                       $isUnitTest = false,
+                                SessionCacheInterface|null $sessionCache = null)
     {
         if (is_null($password)) {
             $password = "password"; // For testing purpose.
         }
+
         if (!$isUnitTest) {
-            $this->provider = new Supporting\CommunicationProvider($solution, $user, $password, $host, $port, $protocol, $fmDataSource);
+            $this->provider = new Supporting\CommunicationProvider($solution, $user, $password, $host, $port, $protocol, $fmDataSource, $sessionCache);
         } else {
-            $this->provider = new Supporting\TestProvider($solution, $user, $password, $host, $port, $protocol, $fmDataSource);
+            $this->provider = new Supporting\TestProvider($solution, $user, $password, $host, $port, $protocol, $fmDataSource, $sessionCache);
         }
     }
 
@@ -264,33 +275,42 @@
     }
 
     /**
-     * Start a transaction which is a serial calling of multiple database operations before the single authentication.
-     * Usually most methods login and logout before/after the database operation, and so a little bit of time is going to
-     * take.
-     * The startCommunication() login and endCommunication() logout, and methods between them don't log in/out, and
-     * it can expect faster operations.
+     * Start a communication scope with a shared authenticated session.
+     *
+     * Usually most methods login and logout before and after each database operation.
+     * By calling startCommunication() and endCommunication(), methods between them don't
+     * log in and out every time, and it can expect faster operations.
+     *
+     * Without a session cache, one authenticated session is kept for the duration of
+     * the current communication scope and discarded when endCommunication() is called.
+     *
+     * With a session cache, the session token is persisted beyond the current communication
+     * scope and reused across requests. If no cached token is available, a new session is
+     * created and stored for future reuse.
+     *
      * @throws Exception
      */
     public function startCommunication(): void
     {
-        try {
-            if ($this->provider->login()) {
-                $this->provider->keepAuth = true;
-            }
-        } catch (Exception $e) {
-            $this->provider->keepAuth = false;
-            throw $e;
-        }
+        $this->provider->startCommunication();
     }
 
     /**
-     * Finish a transaction which is a serial calling of any database operations, and logout.
+     * Finish a communication scope.
+     *
+     * Without a session cache, the authenticated session for the current communication
+     * scope is ended and the server session is logged out.
+     *
+     * With a session cache, the cached token's TTL is renewed if it still matches the
+     * token held by this instance. If another process has replaced the cached token in
+     * the meantime, only this instance's now-stale token is logged out, leaving the
+     * newer cached token intact.
+     *
      * @throws Exception
      */
     public function endCommunication(): void
     {
-        $this->provider->keepAuth = false;
-        $this->provider->logout();
+        $this->provider->endCommunication();
     }
 
     /**
@@ -425,4 +445,44 @@
     {
         $this->provider->excludeTimeStampInException = $value;
     }
+
+    /**
+     * Controls whether failed Data API calls are automatically retried after session invalidation.
+     *
+     * When enabled and a call fails with error 952 (invalid token) or 112 (window missing), the
+     * current session is discarded, a new session is established, and the call is retried once.
+     *
+     * When a session cache is provided to the constructor, retry on token invalidation is always
+     * active regardless of this setting. This flag only has an effect when no session cache is
+     * configured.
+     *
+     * Warning: The retry runs in a fresh session. Any session-scoped state from the original session
+     * is lost — for example, global fields set before the retry will not carry over.
+     * @param bool $value
+     */
+    public function setRetryOnAccessTokenInvalidation(bool $value = true): void
+    {
+        $this->provider->retryOnAccessTokenInvalidation = $value;
+    }
+
+    /**
+     * Overrides the time-to-live (TTL) of the cached FileMaker Data API session token.
+     *
+     * WARNING: Setting a TTL that exceeds the FileMaker Data API session timeout (15 minutes)
+     * will cause the library to use expired tokens, resulting in authentication failures.
+     * Do not use this method unless you fully understand the implications.
+     *
+     * The default TTL is 840 seconds (14 minutes), intentionally set one minute below the
+     * FileMaker Data API session timeout of 15 minutes to ensure the cached token is
+     * invalidated before it expires on the FileMaker Server.
+     * @param int $ttl Time-to-live in seconds. Defaults to 840 seconds (14 minutes).
+     * @throws Exception If a session cache is not set, an exception is thrown.
+     */
+    public function setSessionCacheTtl(int $ttl = 840): void
+    {
+        if ($this->provider->sessionCache === null) {
+            throw new Exception("setSessionCacheTtl() requires a session cache to be configured via the constructor.");
+        }
+        $this->provider->sessionCache->setTtl($ttl);
+    }
 }

src/SessionCache/AbstractSessionCache.php

@@ -0,0 +1,73 @@
+<?php
+
+declare(strict_types=1);
+
+namespace INTERMediator\FileMakerServer\RESTAPI\SessionCache;
+
+/**
+ * Base class for session cache implementations.
+ *
+ * Provides the cache key and TTL to concrete implementations, both of which
+ * are managed internally by the library. The cache key and TTL will not change
+ * during a single PHP request.
+ *
+ * As this cache stores FileMaker Data API session tokens, which are sensitive
+ * credentials granting full API access on behalf of the authenticated user,
+ * implementors must ensure that the underlying cache storage is secure and
+ * not accessible to unauthorized parties.
+ *
+ * To provide a custom cache backend, extend this class and implement
+ * {@see SessionCacheInterface::get()}, {@see SessionCacheInterface::set()},
+ * and {@see SessionCacheInterface::delete()}, using {@see self::$key}
+ * and {@see self::$ttl} in your implementations.
+ *
+ * @see ApcuSessionCache for an example implementation using APCu.
+ * @see SessionCacheInterface for an alternative way to implement session caching without
+ * extending this class.
+ */
+abstract class AbstractSessionCache implements SessionCacheInterface
+{
+    /**
+     * The cache key for the current session.
+     *
+     * Always set by the library via {@see SessionCacheInterface::setKey()} before any cache
+     * operation is performed. Will not change during a single PHP request.
+     * Implementing classes should use this property directly in their
+     * {@see SessionCacheInterface::get()}, {@see SessionCacheInterface::set()},
+     * and {@see SessionCacheInterface::delete()} implementations.
+     */
+    protected string $key;
+
+    /**
+     * The time-to-live in seconds for cached session tokens.
+     *
+     * Set by the library via {@see SessionCacheInterface::setTtl()} before any cache operation
+     * is performed, defaulting to the value provided at construction time.
+     * Will not change during a single PHP request. Implementing classes should
+     * use this property directly in their {@see SessionCacheInterface::set()} implementation.
+     *
+     */
+    protected int $ttl;
+
+    /**
+     * @param int $defaultTtl Default time-to-live in seconds for cached session tokens.
+     *                        Defaults to 840 seconds (14 minutes), reflecting the
+     *                        default FileMaker Data API session timeout. Adjust this
+     *                        value if your FileMaker Server is configured with a
+     *                        different session timeout.
+     */
+    public function __construct(int $defaultTtl = 840)
+    {
+        $this->ttl = $defaultTtl;
+    }
+
+    final public function setKey(string $key): void
+    {
+        $this->key = $key;
+    }
+
+    final public function setTtl(int $ttl): void
+    {
+        $this->ttl = $ttl;
+    }
+}

src/SessionCache/ApcuSessionCache.php

@@ -0,0 +1,83 @@
+<?php
+
+declare(strict_types=1);
+
+namespace INTERMediator\FileMakerServer\RESTAPI\SessionCache;
+
+use RuntimeException;
+
+/**
+ * APCu-based session cache implementation.
+ *
+ * Caches FileMaker Data API session tokens using APCu, which stores data in
+ * shared memory on the server. Note that depending on your setup APCu cache
+ * may be shared across PHP processes on the same server, so cache keys must be
+ * sufficiently unique to avoid collisions between different users and applications.
+ *
+ * Requires that the APCu extension is installed and enabled. See the
+ * documentation here for more information: https://www.php.net/apcu
+ *
+ * As this cache stores sensitive FileMaker Data API session tokens, APCu is
+ * only appropriate in environments where server memory access is properly
+ * restricted.
+ *
+ * Note that cache operations in this implementation are not atomic. While care
+ * has been taken to minimize the risk of race conditions, concurrent requests
+ * sharing the same cache key may occasionally result in redundant
+ * re-authentication against the FileMaker Server. This is considered an
+ * acceptable trade-off given the constraints of the current implementation.
+ *
+ * @package INTER-Mediator\FileMakerServer\RESTAPI\SessionCache
+ * @link https://github.com/msyk/FMDataAPI GitHub Repository
+ * @version 36
+ */
+class ApcuSessionCache extends AbstractSessionCache
+{
+    /**
+     * ApcuSessionCache constructor.
+     * @throws RuntimeException If APCu is not available.
+     */
+    public function __construct()
+    {
+        parent::__construct();
+        if (!function_exists('apcu_enabled') || !apcu_enabled()) {
+            throw new RuntimeException("APCu is required to use ApcuSessionCache.");
+        }
+    }
+
+    /**
+     * Retrieves the cached FileMaker Data API session token for the current session.
+     *
+     * @return string|null The cached session token, or null if no token exists
+     *                     for the current key.
+     */
+    public function get(): string|null
+    {
+        $value = apcu_fetch($this->key, $success);
+        return $success && is_string($value) ? $value : null;
+    }
+
+    /**
+     * Persists a FileMaker Data API session token in APCu.
+     *
+     * @param string $value The FileMaker Data API session token to store.
+     *                      This is a sensitive credential and must be treated as such.
+     * @return bool True on success, false on failure.
+     */
+    public function set(string $value): bool
+    {
+        return apcu_store($this->key, $value, $this->ttl);
+    }
+
+    /**
+     * Deletes the cached FileMaker Data API session token.
+     *
+     * Returns false both when the key does not exist and when deletion fails.
+     *
+     * @return bool True on success, false if the key did not exist or deletion failed.
+     */
+    public function delete(): bool
+    {
+        return apcu_delete($this->key);
+    }
+}