I am trying to update a document in MongoDB but cannot get to checking updated status and responding back to user. Below is my code:
#Autowired
ReactiveMongoTemplate mongoTemplate;
public Mono<String> updateUser(UserIn userIn) {
UserResponse resp = new UserResponse();
mongoTemplate.findAndModify(query, update, User.class)
//.doOnSuccess(bsItem -> {
.flatMap(user -> {
if(user.getItemId().equals(userIn.getId("_id")))
resp.setStatus("Updated");
else
resp.setStatus("Failed");
return Mono.just(resp);
}).subscribe();
return Mono.just(resp.getStatus());
}
Even though update is happening in mongodb, it throws NPE while returning. How to get the control after reactor operator is executed here?
You should almost never subscribe in your own application.
The subscriber is the client that initiated the call in this case it is probably the web application. You application is just relaying the data, so your application is a publisher which means you should not subscribe. The web app subscribes.
Try this.
#Autowired
ReactiveMongoTemplate mongoTemplate;
public Mono<String> updateUser(UserIn userIn) {
return mongoTemplate.findAndModify(query, update, User.class)
.flatMap(user -> {
final UserResponse resp = new UserResponse();
if(user.getItemId().equals(userIn.getId("_id")))
resp.setStatus("Updated");
else
resp.setStatus("Failed");
return Mono.just(resp.getStatus());
});
}
A mono is not like a stream, you fetch, map and return, all in the same mono, like a chain of events. An event chain.
Related
I am trying to integrate Hystrix javanica into my existing java EJB web application and facing 2 issues with running it.
When I try to invoke following service it always returns response from fallback method and I see that the Throwable object in fallback method has "com.netflix.hystrix.exception.HystrixTimeoutException" exception.
Each time this service is triggered, HystrixCommad and fallback methods are called multiple times around 50 times.
Can anyone suggest me with any inputs? Am I missing any configuration?
I am including following libraries in my project.
project libraries
I have setup my aspect file as follows:
<aspectj>
<weaver options="-verbose -showWeaveInfo"></weaver>
<aspects>
<aspect name="com.netflix.hystrix.contrib.javanica.aop.aspectj.HystrixCommandAspect"/>
</aspects>
</aspectj>
Here is my config.properties file in META-INF/config.properties
hystrix.command.default.execution.timeout.enabled=false
Here is my rest service file
#Path("/hystrix")
public class HystrixService {
#GET
#Path("clusterName")
#Produces({ MediaType.APPLICATION_JSON })
public Response getClusterName(#QueryParam("id") int id) {
ClusterCmdBean clusterCmdBean = new ClusterCmdBean();
String result = clusterCmdBean.getClusterNameForId(id);
return Response.ok(result).build();
}
}
Here is my bean class
public class ClusterCmdBean {
#HystrixCommand(groupKey = "ClusterCmdBeanGroup", commandKey = "getClusterNameForId", fallbackMethod = "defaultClusterName")
public String getClusterNameForId(int id) {
if (id > 0) {
return "cluster"+id;
} else {
throw new RuntimeException("command failed");
}
}
public String defaultClusterName(int id, Throwable e) {
return "No cluster - returned from fallback:" + e.getMessage();
}
}
Thanks for the help.
If you want to ensure you are setting the property, you can do that explicitly in the circuit annotation itself:
#HystrixCommand(commandProperties = {
#HystrixProperty(name = "execution.timeout.enabled", value = "false")
})
I would only recommend this for debugging purposes though.
Something that jumps out to me is that Javanica uses AspectJ AOP, which I have never seen work with new MyBean() before. I've always have to use #Autowired with Spring or similar to allow proxying. This could well just be something that is new to me though.
If you set a breakpoint inside the getClusterNameForId can you see in the stack trace that its being called via reflection (which it should be AFAIK)?
Note you can remove commandKey as this will default to the method name. Personally I would also remove groupKey and let it default to the class name.
I'm having trouble following the second step here.
I really don't understand how this sample does anything other than return a simple toast message. How does it utilize the API to display that message?
class EndpointsAsyncTask extends AsyncTask<Pair<Context, String>, Void, String> {
private static MyApi myApiService = null;
private Context context;
#Override
protected String doInBackground(Pair<Context, String>... params) {
if(myApiService == null) { // Only do this once
MyApi.Builder builder = new MyApi.Builder(AndroidHttp.newCompatibleTransport(),
new AndroidJsonFactory(), null)
// options for running against local devappserver
// - 10.0.2.2 is localhost's IP address in Android emulator
// - turn off compression when running against local devappserver
.setRootUrl("http://10.0.2.2:8080/_ah/api/")
.setGoogleClientRequestInitializer(new GoogleClientRequestInitializer() {
#Override
public void initialize(AbstractGoogleClientRequest<?> abstractGoogleClientRequest) throws IOException {
abstractGoogleClientRequest.setDisableGZipContent(true);
}
});
// end options for devappserver
myApiService = builder.build();
}
context = params[0].first;
String name = params[0].second;
try {
return myApiService.sayHi(name).execute().getData();
} catch (IOException e) {
return e.getMessage();
}
}
#Override
protected void onPostExecute(String result) {
Toast.makeText(context, result, Toast.LENGTH_LONG).show();
}
I'm afraid my this sample is too complex for my limited knowledge. How exactly do I "talk" to the Google Endpoints Module when running an app? Specifically, What is EndpointsAsyncTask();?
Are there any resources listing all the methods available to me? Is there a simpler example of an app communicating with a Google Cloud Endpoint?
The service methods available to you are defined by the backend source in section 1.
In the example you posted, this line: myApiService.sayHi(name).execute()
is an actual invocation call to the backend that you defined by annotating #ApiMethod("sayHi") on the method in the MyEndpoint.java class of your backend module.
The reason your Android app defines an EndpointsAsyncTask is because slow operations such as calls that hit the network need to happen off of the UI thread to avoid locking the UI. The demo simply puts the returned value into a Toast but you could modify onPostExecute() to do whatever you'd like with the result.
For more info on Google Endpoints check out:
https://cloud.google.com/appengine/docs/java/endpoints/
And for info about using an Android AsyncTask look here:
http://developer.android.com/reference/android/os/AsyncTask.html
I guess most of us agree, that NIO2 is a fine thing to make use of. Presumed you want to monitor some part of the file system for incoming xml - files it is an easy task now. But what if I want to integrate the things into an existing Java EE application so I don't have to start another service (app-server AND the one which monitors the file system)?
So I have the heavy weight app-server with all the EJB 3.1 stuff and some kind of service monitoring the file system and take appropriate action once a file shows up. Interestingly the appropriate action is to create a Message and send it by JMS and it might be nice to integrate both into the app server.
I tried #Startup but deployment freezes (and I know that I shouldn't make use of I/O in there, was just a try). Anyhow ... any suggestions?
You could create a singleton that loads at startup and delegates the monitoring to an Asynchronous bean
#Singleton
#Startup
public class Initialiser {
#EJB
private FileSystemMonitor fileSystemMonitor;
#PostConstruct
public void init() {
String fileSystemPath = ....;
fileSystemMonitor.poll(fileSystemPath);
}
}
Then the Asynchronous bean looks something like this
#Stateless
public class FileSystemMonitor {
#Asynchronous
public void poll(String fileSystemPath) {
WatchService watcher = ....;
for (;;) {
WatchKey key = null;
try {
key = watcher.take();
for (WatchEvent<?> event: key.pollEvents()) {
WatchEvent.Kind<?> kind = event.kind();
if (kind == StandardWatchEventKinds.OVERFLOW) {
continue; // If events are lost or discarded
}
WatchEvent<Path> watchEvent = (WatchEvent<Path>)event;
//Process files....
}
} catch (InterruptedException e) {
e.printStackTrace();
return;
} finally {
if (key != null) {
boolean valid = key.reset();
if (!valid) break; // If the key is no longer valid, the directory is inaccessible so exit the loop.
}
}
}
}
}
Might help if you specified what server you're using, but have you considered implementing a JMX based service ? It's a bit more "neutral" than EJB, is more appropriate for a background service and has fewer restrictions.
I was told that I shouldn't cache channels in Silverlight/WCF because they may become faulted and unsuable. Can somone show me some sample code that would prove it can happen.
Call a service to prove the connection can work (i.e. no bogus URL)
Make a second call that fouls the channel by causing it to go into a faulted condition
Repeat the first call, which would fail.
In my own testing, the key is whether the binding you're using is session-oriented or not. If you're using a stateless binding like BasicHttpBinding, you can muck up the channel all you want and you're good. For instance, I've got a WCF service using the BasicHttpBinding that looks like this -- note specifically the Channel.Abort() call in SayGoodbye():
public class HelloWorldService : IHelloWorldService
{
public string SayHello()
{
return "Hello.";
}
public string SayGoodbye()
{
OperationContext.Current.Channel.Abort();
return "Goodbye.";
}
}
And the Silverlight client code looks like this (ugly as hell, sorry).
public partial class ServiceTestPage : Page
{
HelloWorldServiceClient client;
public ServiceTestPage()
{
InitializeComponent();
client = new HelloWorldServiceClient();
client.SayHelloCompleted += new EventHandler<SayHelloCompletedEventArgs>(client_SayHelloCompleted);
client.SayGoodbyeCompleted += new EventHandler<SayGoodbyeCompletedEventArgs>(client_SayGoodbyeCompleted);
client.SayHelloAsync();
}
void client_SayHelloCompleted(object sender, SayHelloCompletedEventArgs e)
{
if (e.Error == null)
{
Debug.WriteLine("Called SayHello() with result: {0}.", e.Result);
client.SayGoodbyeAsync();
}
else
{
Debug.WriteLine("Called SayHello() with the error: {0}", e.Error.ToString());
}
}
void client_SayGoodbyeCompleted(object sender, SayGoodbyeCompletedEventArgs e)
{
if (e.Error == null)
{
Debug.WriteLine("Called SayGoodbye() with result: {0}.");
}
else
{
Debug.WriteLine("Called SayGoodbye() with the error: {0}", e.Error.ToString());
}
client.SayHelloAsync(); // start over
}
}
And it'll loop around infinitely as long as you want.
But if you're using a session-oriented binding like Net.TCP or HttpPollingDuplex, you've got to be much more careful about your channel handling. If that's the case, then of course you're caching your proxy client, right? What you have to do in that instance is to catch the Channel_Faulted event, abort the client, and then recreate it, and of course, re-establish all your event-handlers. Kind of a pain.
On a side note, when it comes to using a duplex binding, the best approach that I've found (I'm open to others) is to create a wrapper around my proxy client that does three things:
(1) Transforms the obnoxious event-raising code generated by the "Add Service Reference" dialog box into a far-more-useful continuation-passing pattern.
(2) Wraps each of the events raised from the server-side, so that the client can subscribe to the event on my wrapper, not the event on the proxy client itself, since the proxy client itself may have to be deleted and recreated.
(3) Handles the ChannelFaulted event, and (several times, with a timeout) attempts to recreate the proxy client. If it succeeds, it automatically resubscribes all of its event wrappers, and if it fails, it throws a real ClientFaulted event which in effect means, "You're screwed, try again later."
It's a pain, since it seems like this is the sort of thing that should have been included with the MS-generated code in the first place. But it sure fixes a whole lot of problems. One of these days I'll see if I can get this wrapper working with T4 templates.
Having a lot of problems trying to consume a simple service operator in a WCF Data Service from Silverlight. I've verified the following service operator is working by testing it in the browser:
[WebGet]
public IQueryable<SecurityRole> GetSecurityRolesForUser(string userName) {
string currentUsername = HttpContext.Current.User.Identity.Name;
// if username passed in, verify current user is admin and is getting someone else's permissions
if (!string.IsNullOrEmpty(userName)) {
if (!SecurityHelper.IsUserAdministrator(currentUsername))
throw new DataServiceException(401, Properties.Resources.RequiestDeniedInsufficientPermissions);
} else // else nothing passed in, so get the current user's permissions
userName = currentUsername;
return SecurityHelper.GetUserRoles(userName).AsQueryable<SecurityRole>();
}
However no matter how I try using different methods I've found in various online resources, I've been unable to consume the data. I've tried using the BeginExecute() method on boht the DataServiceContext and DataServiceQuery, but I keep getting errors or no data returned in the EndExecute method. I've got to be doing something simple wrong... here's my SL code:
private void InitUserSecurityRoles() {
MyEntities context = new MyEntities(new Uri("http://localhost:9999/MyService.svc"));
context.BeginExecute<SecurityRole>(new Uri("http://localhost:9999/MyService.svc/GetSecurityRolesForUser"), OnComplete, context);
DataServiceQuery<SecurityRole> query = context.CreateQuery<SecurityRole>("GetSecurityRolesForUser");
query.BeginExecute(OnComplete, query);
}
private void OnComplete(IAsyncResult result) {
OnDemandEntities context = result.AsyncState as OnDemandEntities;
var x = context.EndExecute<SecurityRole>(result);
}
Any tips? I'm at a loss right now on how to properly consume a custom service operator from Silverlight (or even sync using my unit test project) from a OData service. I've also verified via Fiddler that I'm passing along the correct authentication stuff as well, even going to far as explicitly set the credentials. Just to be safe, I even removed the logic from the service operator that does the security trimming.
Got it working thanks to #kaevans (http://blogs.msdn.com/b/kaevans):
private void InitUserSecurityRoles() {
DataServiceContext context = new DataServiceContext(new Uri("http://localhost:9999/MyService.svc"));
context.BeginExecute<SecurityRole>(new Uri("/GetSecurityRolesForUser", UriKind.Relative),
(result) => {
SmartDispatcher.BeginInvoke(
() => {
var roles = context.EndExecute<SecurityRole>(result);
UserSecurityRoles = new List<SecurityRole>();
foreach (var item in roles) {
UserSecurityRoles.Add(item);
}
});
}, null);
}
I had to create the SmartDispatcher because this is happening in a ViewModel. Otherwise I could have just used the static Dispatcher.BeginInvoke(). Couldn't get the roles variable to insert into my UserSecurityRoles (type List) directly for sone reason using various techniques, so I just dropped down to adding it manually (code isn't called often nor is it a collection exceeding more than 10 items max... most are <5).