public function startAuthentication(Request $request, Response $response) {
		$callbackUri = $request->getUri();

		if (!isset($this->options['server'])) {
			throw new Exception('Missing "server" option for SingleSignOnRedirect entry point. Please specifiy one using the entryPointOptions setting.', 1351690358);
		}
		$ssoServer = $this->ssoServerFactory->create($this->options['server']);
		$ssoClient = $this->ssoClientFactory->create();

		$redirectUri = $ssoServer->buildAuthenticationEndpointUri($ssoClient, $callbackUri);
		$response->setStatus(303);
		$response->setHeader('Location', $redirectUri);
	}