是否有任何机制或方法或步骤来检测从应用程序到KAA服务器的端点（KAA SDK）连接。
如果不是，那么我们如何通过远程识别故障设备？或者我们如何识别在现场部署设备后无法与KAA服务器通信的设备？
如何实现这一要求以释放物联网的力量？
答案 0 :(得分：5)
如果您的终端遇到一些连接到Kaa服务器的问题a＆＃34;故障转移＆＃34;会发生。
因此，您必须定义自己的故障转移策略并为您的Kaa客户端设置它。每次故障转移发生时，都会调用策略onFialover()方法。
下面您可以看到Java SDK的代码示例。
import org.kaaproject.kaa.client.DesktopKaaPlatformContext;
import org.kaaproject.kaa.client.Kaa;
import org.kaaproject.kaa.client.KaaClient;
import org.kaaproject.kaa.client.SimpleKaaClientStateListener;
import org.kaaproject.kaa.client.channel.failover.FailoverDecision;
import org.kaaproject.kaa.client.channel.failover.FailoverStatus;
import org.kaaproject.kaa.client.channel.failover.strategies.DefaultFailoverStrategy;
import org.kaaproject.kaa.client.exceptions.KaaRuntimeException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
/**
* A demo application that shows how to use the Kaa credentials API.
*/
public class CredentialsDemo {
private static final Logger LOG = LoggerFactory.getLogger(CredentialsDemo.class);
private static KaaClient kaaClient;
public static void main(String[] args) throws InterruptedException, IOException {
LOG.info("Demo application started");
try {
// Create a Kaa client and add a startup listener
kaaClient = Kaa.newClient(new DesktopKaaPlatformContext(), new SimpleKaaClientStateListener() {
@Override
public void onStarted() {
super.onStarted();
LOG.info("Kaa client started");
}
}, true);
kaaClient.setFailoverStrategy(new CustomFailoverStrategy());
kaaClient.start();
// ... Do some work ...
LOG.info("Stopping application.");
kaaClient.stop();
} catch (KaaRuntimeException e) {
LOG.info("Cannot connect to server - no credentials found.");
LOG.info("Stopping application.");
}
}
// Give a possibility to manage device behavior when it loses connection
// or has other problems dealing with Kaa server.
private static class CustomFailoverStrategy extends DefaultFailoverStrategy {
@Override
public FailoverDecision onFailover(FailoverStatus failoverStatus) {
LOG.info("Failover happen. Failover type: " + failoverStatus);
// See enum DefaultFailoverStrategy from package org.kaaproject.kaa.client.channel.failover
// to list all possible values
switch (failoverStatus) {
case CURRENT_BOOTSTRAP_SERVER_NA:
LOG.info("Current Bootstrap server is not available. Trying connect to another one.");
// ... Do some recovery, send notification messages, etc. ...
// Trying to connect to another bootstrap node one-by-one every 5 seconds
return new FailoverDecision(FailoverDecision.FailoverAction.USE_NEXT_BOOTSTRAP, 5L, TimeUnit.SECONDS);
default:
return super.onFailover(failoverStatus);
}
}
}
}
更新（2016/10/28）
从服务器端，您可以检查端点凭据状态，如下面的代码中的方法checkCredentialsStatus()所示。状态IN_USE显示端点至少有一次成功的连接尝试。
不幸的是，在当前的Kaa版本中，没有办法直接检查端点是否连接到服务器。我在代码示例后描述它们。
package org.kaaproject.kaa.examples.credentials.kaa;
import org.kaaproject.kaa.common.dto.ApplicationDto;
import org.kaaproject.kaa.common.dto.admin.AuthResultDto;
import org.kaaproject.kaa.common.dto.credentials.CredentialsStatus;
import org.kaaproject.kaa.examples.credentials.utils.IOUtils;
import org.kaaproject.kaa.server.common.admin.AdminClient;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.List;
public class KaaAdminManager {
private static final Logger LOG = LoggerFactory.getLogger(KaaAdminManager.class);
private static final int DEFAULT_KAA_PORT = 8080;
private static final String APPLICATION_NAME = "Credentials demo";
public String tenantAdminUsername = "admin";
public String tenantAdminPassword = "admin123";
private AdminClient adminClient;
public KaaAdminManager(String sandboxIp) {
this.adminClient = new AdminClient(sandboxIp, DEFAULT_KAA_PORT);
}
// ...
/**
* Check credentials status for getting information
* @return credential status
*/
public void checkCredentialsStatus() {
LOG.info("Enter endpoint ID:");
// Reads endpoint ID (aka "endpoint key hash") from user input
String endpointId = IOUtils.getUserInput().trim();
LOG.info("Getting credentials status...");
try {
ApplicationDto app = getApplicationByName(APPLICATION_NAME);
String appToken = app.getApplicationToken();
// CredentialsStatus can be: AVAILABLE, IN_USE, REVOKED
// if endpoint is not found on Kaa server, exception will be thrown
CredentialsStatus status = adminClient.getCredentialsStatus(appToken, endpointId);
LOG.info("Credentials for endpoint ID = {} are now in status: {}", endpointId, status.toString());
} catch (Exception e) {
LOG.error("Get credentials status for endpoint ID = {} failed. Error: {}", endpointId, e.getMessage());
}
}
/**
* Get application object by specified application name
*/
private ApplicationDto getApplicationByName(String applicationName) {
checkAuthorizationAndLogin();
try {
List<ApplicationDto> applications = adminClient.getApplications();
for (ApplicationDto application : applications) {
if (application.getName().trim().equals(applicationName)) {
return application;
}
}
} catch (Exception e) {
LOG.error("Exception has occurred: " + e.getMessage());
}
return null;
}
/**
* Checks authorization and log in
*/
private void checkAuthorizationAndLogin() {
if (!checkAuth()) {
adminClient.login(tenantAdminUsername, tenantAdminPassword);
}
}
/**
* Do authorization check
* @return true if user is authorized, false otherwise
*/
private boolean checkAuth() {
AuthResultDto.Result authResult = null;
try {
authResult = adminClient.checkAuth().getAuthResult();
} catch (Exception e) {
LOG.error("Exception has occurred: " + e.getMessage());
}
return authResult == AuthResultDto.Result.OK;
}
}
您可以在GitHub上的Kaa KaaAdminManager Credentials Demo Application的sample-apps project课程中查看更多使用AdminClient的示例。
了解变通方法
*要有效使用Kaa Data Collection功能，您必须在所选Log appender的设置中添加此类元数据（在Kaa Admin UI中）：＆＃34; Endpoint key hash＆＃34; （与＆＃34;端点ID＆＃34;相同），＆＃34;时间戳＆＃34;。这将自动将所需字段添加到从端点接收的每个日志记录中。
答案 1 :(得分：0)
我自己是Kaa的新手并且不确定是否有一种方法直接在SDK中确定，但是解决方法是你可以有一个额外的端点，你可以定期向所有其他端点发送一个事件并希望得到答复。当端点没有回复时，您知道存在问题。