Add services yml file and service class

cern_ldap_api.services.yml

+services:
+  cern_lda_api.cernldap:
+    class: Drupal\cern_ldap_api\CERNLdapService
\ No newline at end of file

src/CERNLdapService.php

@@ -2,4 +2,23 @@
 
 namespace Drupal\cern_ldap_api;
 
-Class CERNLdapService
+/**
\ No newline at end of file
+ * CERNLdapService is a service to contact CERN Ldap service
+ */
+
+Class CERNLdapService {
+  private $server_host = "xldap.cern.ch";
+
+  /**
+   * Resolves emails for an e-group
+   * @param string $egroup
+   *   The egroup name in simple formar, ex: drupal-admins
+   * @param bool $recursive
+   *   Flag to enable/disable recursive lookup of inner e-groups
+   */
+  public function resolveEgroup($egroup, $recursive) {
+      
+  }
+
+
+}
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