I am using python code to control a drone. I am using two RC_CHANNLES_OVERRIDE functions to send data to the autopilot. I don't want both of them to send the data simultaneously. TO be able to control the drone I have to pass just one of them. I want it to be depending on the value of channel5 for example, so if channel 5 is 1900 send the value of the first controller, if channel5 is 1100, send the value of the second controller. so, my question is how to get the current value of a specific RC channel?
Related
I am working on building streaming APIs for client/server communication using Axon and ServerSentEvents and not sure if it is possible to stream and identify multiple different events using Axon query update emitter and subscription query.
I am using Axon QueryUpdateEmitter.emit to emit the events from a projection based on different events. Emitter is emitting in projection whereas subscription query is taking place in the REST API that is supposed to stream the server sent events to client.
For example,
I want to emit 3 different events for a use case which creates, updates and deletes an entity.
I am wondering if we can emit different types of data from different events but still combine in one stream, i.e. send actual object upon entity create and update in the emitter but, since I don’t have any entity/data to emit in case of delete, I thinking whether to send a simple message for delete?
I also want a way to specify the type of event while emitting so when ServerSentEvent is build from subscription query, I can specify the type/action (for ex, differentiate between create or update event) along with data.
Main idea is to emit different events and add them in one stream despite knowing all events may not return exactly same data (create, update vs. delete) as part of one subscription query and to be able to accurately identify the event and specify in the stream of ServerSentEvents with appropriate event type.
Any ideas on how I can achieve this?
Here's how I am emitting an event upon creation using QueryUpdateEmitter:
#EventHandler
public void on(LibraryCreatedEvent event, #Timestamp Instant timestamp) {
final LibrarySummaryEntity librarySummary = mapper.createdEventToLibrarySummaryEntity(event, timestamp);
repository.save(librarySummary);
log.debug("On {}: Saved the first summary of the library named {}", event.getClass().getSimpleName(), event.getName());
queryUpdateEmitter.emit(
AllLibrarySummariesQuery.class,
query -> true,
librarySummary
);
log.debug("emitted library summary: {}", librarySummary.getId());
}
Since I need to distinguish between create and update so I tried using GenericSubscriptionQueryUpdateMessage.asUpdateMessage upon update event and added some metadata along with it but not sure if that is in the right direction as I am not sure how to retrieve that information during subscription query.
Map<String, String> map = new HashMap();
map.put(“Book Updated”, event.getLibraryId());
queryUpdateEmitter.emit(AllLibrarySummariesQuery.class,query → true,GenericSubscriptionQueryUpdateMessage.asUpdateMessage(librarySummary).withMetaData(map));
Here's how I am creating subscription query:
SubscriptionQueryResult<List<LibrarySummaryEntity>, LibrarySummaryEntity> result = queryGateway.subscriptionQuery(new AllLibrarySummariesQuery(),ResponseTypes.multipleInstancesOf(LibrarySummaryEntity.class),ResponseTypes.instanceOf(LibrarySummaryEntity.class));
And the part where I am building server sent event:
(.event is where I want to specify the type of event - create/update/delete and send the applicable data accordingly)
Flux<ServerSentEvent<LibrarySummaryResponseDto>> sseStream = result.initialResult()
.flatMapMany(Flux::fromIterable).map(value -> mapper.libraryEntityToResponseDto(value))
.concatWith((streamingTimeout == -1)? result.updates().map(value -> mapper.libraryEntityToResponseDto(value)): result.updates().take(Duration.ofMinutes(streamingTimeout)).map(value -> mapper.libraryEntityToResponseDto(value)))
.log()
.map(created -> ServerSentEvent.<LibrarySummaryResponseDto>builder()
.id(created.getId())
.event("library creation")
.data(created).build())
.doOnComplete(() -> {log.info("streaming completed");})
.doFinally(signal -> result.close());
As long as the object you return matches the expected type when making the subscription query, you should be good!
Note that this means you will have to make a response object that can fit your scenarios. Whether response is something you'd emit as the update (through the QueryUpdateEmitter) or a map operation from where you return the subscription query, is a different question, though.
Ideally, you'd decouple your internal messages from what you send outward, like with SSE. To move to a more specific solution, you could benefit from having a Flux response type. You can simply attach any mapping operations to adjust the responses emitted by the QueryUpdateEmitter to your desired SSE format.
Concluding, the short answer is "yes you can," as long as the emitted response object matches the expected update type when dispatching the subscription query on the QueryGateway.
Is there a way to send multiple transactions to a counterparty without using a loop in the flow? Sending one tx a time in a loop impacts the performance significantly since Suspendable behaviour doesn't work well with large volumn of txes.
At some point in time, T, an initiator may be interested in sending N numbers of transactions to a regulator/counterparty. But the current SendTransactionsFlow only send one tx at a time. And on the other side, it ReceiveTransactionFlow to record one by one.
My current code
relevantTxes.forEach{
subFlow(SendTransactionFlow(session, signedTx))
}
Is there a way to do something along the line of
subFlow(SendTransactionFlow(session, relevantTxes))
You can send the list of transactions without invoking a subflow by using send and receive.
On the sender's side:
val session = initiateFlow(otherParty)
session.send(relevantTxes)
On the receiver's side:
session.receive<List<SignedTransaction>>().unwrap { relevantTxes -> relevantTxes }
Suppose I have a Redux store. Its state has the userCoordinates field
with the user's current coordinates:
{
userCoordinates: [3.1457, 2.1728],
...
}
Then suppose the store has 20 more fields with data that depends on the
coordinates:
{
...
nearbyFriends: ["Bob", "Jimmy"],
nearbyShops: ["Point & Click tools", "Bobby Ray's"],
address: "42 Enth Street, Townsville, Countryland",
weather: "Cloudy",
...
}
Values in all of these fields are loaded over HTTP from
various services, one separate request for each field.
Now suppose the user's geolocation is updated, and an action is dispatched that
changes the value of userCoordinates:
dispatch(updateCoords([1.6180, 1.4142]));
Now userCoordinates has new coordinates and all 20 other fields have invalid data.
If the goal is just to keep all the fields "eventually" valid, where do I make the requests to fetch the new data?
How the method changes if I use React-Redux and there are lots of components using many different combinations of these fields, with some fields used by more than one component and some fields not used at all?
Depending on how this is architected, I would do one of two things.
1: Compare states in your reducer. If there is a change in the user coordinates in the state, you could add something to the store like updateNeeded: true, then have a check wherever you are loading your other data so that if updateNeeded is true, you fire an ajax call to go get new data from the server.
2: If it is set up the right way, you could used componentWillReceiveProps to compare the props. If there is a change in userCoordinates, dispatch an action to go get the other data fields.
Of course, this would just be easier if you could just get all the data with one call...
Say I have a resource defined such that the service https://api.mydomainname.com/v1/stores/ABC/order where "ABC" has a direct relation to a Developer App entry. I also have a Custom Attribute for the maximum number of seconds that can elapse between calls; if the time between calls exceeds that threshold, I'd like to take an action (make an call, raise a Nagios alert, etc).
Example:
ABC (api key: 54c34ce0f7691840093bfba55a10c782) has a 300s elapsed time threshold
XYZ (api key: af9843af2d190f72481183a8645659ac) has a 600s elapsed time threshold
Do we have any ideas on how to do this on for all related message processors in an Organization?
I do not want to have to have a call to check if the threshold has been exceeded.
I'm thinking I have to push this further down to the actual service, but if there is an Apigee based potential solution, I'd be interested.
One option is to use the <LookupCache> and <PopulateCache> policies. Caching is distributed (across MPs) by default.
You could store the threshold value (300s/600s/etc) as a custom attribute on the develop app. After <VerifyAPIKey> policy, this attribute value should be automatically populated and you can use that reference in the <PopulateCache> policy. Example flow steps:
VerifyAPIKey (will get the threshold value for populate.
LookupCache
If cache hit, continue. Else, raise custom fault or execute custom logic.
PopulateCache to create/update entry, reading expiry from variable reference of attribute populated by #1). If the entry already exists, it will re-populate the entry with fresh expiration, essentially reseting the last request time.
I have a method , it takes some time like 4 minutes , for that i want show a text in the page about completion of method like for 1 min, 2 min, 3 min and some data i want to store session and that i want to access in ajax timer and want to show the status of the method like completion state for make user to understand how much the method completed.
Thanks
Use the HeartBeat design pattern.
Your javascript will call a custom HTTP handler thru Ajax calls (every x seconds), and that handler will return status information to the javascript using JSON data. Next, you will update your progress control according to that data.