Develop Reference

Apache Flink Kafka Stream Processing based on conditions

Am building a wrapper library using apache-flink where I am listening(consuming) from multiple topics and I have a set of applications that want to process the messages from those topics.
Example :
I have 10 applications app1, app2, app3 ... app10 (each of them is a java library part of the same on-prem project, ie., all 10 jars are part of same .war file)
out of which only 5 are supposed to consume the messages coming to the consumer group. I am able to do filtering for 5 apps with the help of filter function.
The challenge is in the strStream.process(executionServiceInterface) function, where app1 provides an implementation class for ExceucionServiceInterface as ExecutionServiceApp1Impl and similary app2 provides ExecutionServiceApp2Impl.
when there are multiple implementations available spring wants us to provide #Qualifier annotation or #Primary has to be marked on the implementations (ExecutionServiceApp1Impl , ExecutionServiceApp2Impl).
But I don't really want to do this. As am building a generic wrapper library that should support any no of such applications (app1, app2 etc) and all of them should be able to implement their own implementation logic(ExecutionServiceApp1Impl , ExecutionServiceApp2Impl).
Can someone help me here ? how to solve this ?
Below is the code for reference.
#Autowired
private ExceucionServiceInterface executionServiceInterface;
public void init(){
StreamExecutionEnvironment environment = StreamExecutionEnvironment.getExecutionEnvironment();
FlinkKafkaConsumer011<String> consumer = createStringConsumer(topicList, kafkaAddress, kafkaGroup);
if (consumer != null) {
DataStream<String> strStream = environment.addSource(consumer);
strStream.filter(filterFunctionInterface).process(executionServiceInterface);
}
}
public FlinkKafkaConsumer011<String> createStringConsumer(List<String> listOfTopics, String kafkaAddress, String kafkaGroup) throws Exception {
FlinkKafkaConsumer011<String> myConsumer = null;
try {
Properties props = new Properties();
props.setProperty("bootstrap.servers", kafkaAddress);
props.setProperty("group.id", kafkaGroup);
myConsumer = new FlinkKafkaConsumer011<>(listOfTopics, new SimpleStringSchema(), props);
} catch(Exception e) {
throw e;
}
return myConsumer;
}
Many thanks in advance!!

Solved this problem by using Reflection, below is the code that solved the issue.
Note : this requires me to know the list of fully qualified classNames and method names along with their parameters.
#Component
public class SampleJobExecutor extends ProcessFunction<String, String> {
#Autowired
MyAppProperties myAppProperties;
#Override
public void processElement(String inputMessage, ProcessFunction<String, String>.Context context,
Collector<String> collector) throws Exception {
String className = null;
String methodName = null;
try {
Map<String, List<String>> map = myAppProperties.getMapOfImplementors();
JSONObject json = new JSONObject(inputMessage);
if (json != null && json.has("appName")) {
className = map.get(json.getString("appName")).get(0);
methodName = map.get(json.getString("appName")).get(1);
}
Class<?> forName = Class.forName(className);
Object job = forName.newInstance();
Method method = forName.getDeclaredMethod(methodName, String.class);
method.invoke(job , inputMessage);
} catch (Exception e) {
e.printStackTrace();
}
}

Rxjava2 + Retrofit2 + Android. Best way to do hundreds of network calls

I have an app. I have a big button that allows the user to sync all their data at once to the cloud. A re-sync feature that allows them to send all their data again. (300+ entries)
I am using RXjava2 and retrofit2. I have my unit test working with a single call. However I need to make N network calls.
What I want to avoid is having the observable call the next item in a queue. I am at the point where I need to implement my runnable. I have seen a bit about Maps but I have not seen anyone use it as a queue. Also I want to avoid having one item fail and it report back as ALL items fail, like the Zip feature would do. Should I just do the nasty manager class that keeps track of a queue? Or is there a cleaner way to send several hundred items?
NOTE: SOLUTION CANNOT DEPEND ON JAVA8 / LAMBDAS. That has proved to be way more work than is justified.
Note all items are the same object.
#Test
public void test_Upload() {
TestSubscriber<Record> testSubscriber = new TestSubscriber<>();
ClientSecureDataToolKit clientSecureDataToolKit = ClientSecureDataToolKit.getClientSecureDataKit();
clientSecureDataToolKit.putUserDataToSDK(mPayloadSecureDataToolKit).subscribe(testSubscriber);
testSubscriber.awaitTerminalEvent();
testSubscriber.assertNoErrors();
testSubscriber.assertValueCount(1);
testSubscriber.assertCompleted();
}
My helper to gather and send all my items
public class SecureDataToolKitHelper {
private final static String TAG = "SecureDataToolKitHelper";
private final static SimpleDateFormat timeStampSimpleDateFormat =
new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
public static void uploadAll(Context context, RuntimeExceptionDao<EventModel, UUID> eventDao) {
List<EventModel> eventModels = eventDao.queryForAll();
QueryBuilder<EventModel, UUID> eventsQuery = eventDao.queryBuilder();
String[] columns = {...};
eventsQuery.selectColumns(columns);
try {
List<EventModel> models;
models = eventsQuery.orderBy("timeStamp", false).query();
if (models == null || models.size() == 0) {
return;
}
ArrayList<PayloadSecureDataToolKit> toSendList = new ArrayList<>();
for (EventModel eventModel : models) {
try {
PayloadSecureDataToolKit payloadSecureDataToolKit = new PayloadSecureDataToolKit();
if (eventModel != null) {
// map my items ... not shown
toSendList.add(payloadSecureDataToolKit);
}
} catch (Exception e) {
Log.e(TAG, "Error adding payload! " + e + " ..... Skipping entry");
}
}
doAllNetworkCalls(toSendList);
} catch (SQLException e) {
e.printStackTrace();
}
}
my Retrofit stuff
public class ClientSecureDataToolKit {
private static ClientSecureDataToolKit mClientSecureDataToolKit;
private static Retrofit mRetrofit;
private ClientSecureDataToolKit(){
mRetrofit = new Retrofit.Builder()
.baseUrl(Utilities.getSecureDataToolkitURL())
.addCallAdapterFactory(RxJavaCallAdapterFactory.create())
.addConverterFactory(GsonConverterFactory.create())
.build();
}
public static ClientSecureDataToolKit getClientSecureDataKit(){
if(mClientSecureDataToolKit == null){
mClientSecureDataToolKit = new ClientSecureDataToolKit();
}
return mClientSecureDataToolKit;
}
public Observable<Record> putUserDataToSDK(PayloadSecureDataToolKit payloadSecureDataToolKit){
InterfaceSecureDataToolKit interfaceSecureDataToolKit = mRetrofit.create(InterfaceSecureDataToolKit.class);
Observable<Record> observable = interfaceSecureDataToolKit.putRecord(NetworkUtils.SECURE_DATA_TOOL_KIT_AUTH, payloadSecureDataToolKit);
return observable;
}
}
public interface InterfaceSecureDataToolKit {
#Headers({
"Content-Type: application/json"
})
#POST("/api/create")
Observable<Record> putRecord(#Query("api_token") String api_token, #Body PayloadSecureDataToolKit payloadSecureDataToolKit);
}
Update. I have been trying to apply this answer to not much luck. I am running out of steam for tonight. I am trying to implement this as a unit test, like I did for the original call for one item.. It looks like something is not right with use of lambda maybe..
public class RxJavaBatchTest {
Context context;
final static List<EventModel> models = new ArrayList<>();
#Before
public void before() throws Exception {
context = new MockContext();
EventModel eventModel = new EventModel();
//manually set all my eventmodel data here.. not shown
eventModel.setSampleId("SAMPLE0");
models.add(eventModel);
eventModel.setSampleId("SAMPLE1");
models.add(eventModel);
eventModel.setSampleId("SAMPLE3");
models.add(eventModel);
}
#Test
public void testSetupData() {
Assert.assertEquals(3, models.size());
}
#Test
public void testBatchSDK_Upload() {
Callable<List<EventModel> > callable = new Callable<List<EventModel> >() {
#Override
public List<EventModel> call() throws Exception {
return models;
}
};
Observable.fromCallable(callable)
.flatMapIterable(models -> models)
.flatMap(eventModel -> {
PayloadSecureDataToolKit payloadSecureDataToolKit = new PayloadSecureDataToolKit(eventModel);
return doNetworkCall(payloadSecureDataToolKit) // I assume this is just my normal network call.. I am getting incompatibility errors when I apply a testsubscriber...
.subscribeOn(Schedulers.io());
}, true, 1);
}
private Observable<Record> doNetworkCall(PayloadSecureDataToolKit payloadSecureDataToolKit) {
ClientSecureDataToolKit clientSecureDataToolKit = ClientSecureDataToolKit.getClientSecureDataKit();
Observable observable = clientSecureDataToolKit.putUserDataToSDK(payloadSecureDataToolKit);//.subscribe((Observer<? super Record>) testSubscriber);
return observable;
}
Result is..
An exception has occurred in the compiler (1.8.0_112-release). Please file a bug against the Java compiler via the Java bug reporting page (http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com) for duplicates. Include your program and the following diagnostic in your report. Thank you.
com.sun.tools.javac.code.Symbol$CompletionFailure: class file for java.lang.invoke.MethodType not found
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':app:compile<MyBuildFlavorhere>UnitTestJavaWithJavac'.
> Compilation failed; see the compiler error output for details.
Edit. No longer trying Lambdas. Even after setting up the path on my mac, javahome to point to 1.8, etc. I could not get it to work. If this was a newer project I would push harder. However as this is an inherited android application written by web developers trying android, it is just not a great option. Nor is it worth the time sink to get it working. Already into the days of this assignment instead of the half day it should have taken.
I could not find a good non lambda flatmap example. I tried it myself and it was getting messy.

If I understand you correctly, you want to make your calls in parallel?
So rx-y way of doing this would be something like:
Observable.fromCallable(() -> eventsQuery.orderBy("timeStamp", false).query())
.flatMapIterable(models -> models)
.flatMap(model -> {
// map your model
//avoid throwing exceptions in a chain, just return Observable.error(e) if you really need to
//try to wrap your methods that throw exceptions in an Observable via Observable.fromCallable()
return doNetworkCall(someParameter)
.subscribeOn(Schedulers.io());
}, true /*because you don't want to terminate a stream if error occurs*/, maxConcurrent /* specify number of concurrent calls, typically available processors + 1 */)
.subscribe(result -> {/* handle result */}, error -> {/* handle error */});
In your ClientSecureDataToolKit move this part into constructor
InterfaceSecureDataToolKit interfaceSecureDataToolKit = mRetrofit.create(InterfaceSecureDataToolKit.class);

How to get Workflow event type and Processstep name or Arguments in to java service in AEM?

I created a workflow for whenever I upload or remove asset from /content/dam/MyAsset folder I am able to Triggering JavaServices. I create two launcher with Created Event Type and Removed Event Type.
I need to get That event Type and Process step name or arguments in to Services
inside Triggering execute function
Here is My Code:
public void execute(WorkItem arg0, WorkflowSession arg1, MetaDataMap arg2)
throws WorkflowException
{
log.info("Workflow created ::::: ");
}
Is there any way to get Launcher event type and process arguments]to Services ?

You can not get launcher event type as that information is not passed down to the workflow. What you could do is check the payload to identify if the node exists or not. The workflow called on removal will have path to the node that is removed and if you try to resolve that path it will give you exception (yeah, bad approach but thats the only possibility).
For the process step arguments passed, all that information is available in meta data. Look into arg0.getWorkflowData().getMetaDataMap().get("MyIDkey",<Type>); where arg0 is your WorkItem instance.

Why don't you use a org.osgi.service.event.EventHandler instead? You will have all the information you need. Here is a small code snippet that waits for an event and adds the relevant data into a map that is then passed to the JobManager to generate a new Job that is executed by a matching JobConsumer:
import org.apache.sling.event.jobs.Job;
import org.apache.sling.event.jobs.JobManager;
import org.apache.sling.event.jobs.consumer.JobConsumer;
// and more imports...
#Service
#Component(immediate = true, policy = ConfigurationPolicy.OPTIONAL, description = "Listen to page modification events.")
#Properties(value = { #Property(name = "event.topics", value = { PageEvent.EVENT_TOPIC, DamEvent.EVENT_TOPIC}, propertyPrivate = true),
#Property(name = JobConsumer.PROPERTY_TOPICS, value = ModificationEventHandler.JOB_TOPICS, propertyPrivate = true) })
public class ModificationEventHandler implements EventHandler, JobConsumer {
/**
* Modification Job Topics.
*/
public static final String JOB_TOPICS = "de/rockware/aem/modification";
#Reference
private JobManager jobManager;
#Override
public void handleEvent(Event event) {
logger.trace("Checking event.");
PageEvent pageEvent = PageEvent.fromEvent(event);
DamEvent damEvent = DamEvent.fromEvent(event);
Map<String, Object> properties = new HashMap<>();
if (damEvent != null) {
// DamEvent is not serializable, so we cannot add the complete event to the map.
logger.trace("Event on {} is a dam event ({}).", damEvent.getAssetPath(), damEvent.getType().name());
properties.put(DAM_EVENT_ASSET_PATH, damEvent.getAssetPath());
}
if (pageEvent != null) {
logger.trace("Event is a page event.");
properties.put(PAGE_EVENT, pageEvent);
}
logger.trace("Adding new job.");
jobManager.addJob(JOB_TOPICS, properties);
}
#Override
public JobResult process(Job job) {
if (job.getProperty(PAGE_EVENT) != null) {
PageEvent pageEvent = (PageEvent) job.getProperty(PAGE_EVENT);
if(pageEvent.isLocal()) {
Iterator<PageModification> modificationsIterator;
modificationsIterator = pageEvent.getModifications();
while (modificationsIterator.hasNext()) {
PageModification modification = modificationsIterator.next();
logger.info("Handling modification {} on path {}.", modification.getType(), modification.getPath());
if(isRelevantModification(modification.getType())) {
logger.info(modification.getPath());
}
}
} else {
logger.trace("Page event is not local.");
}
} else if (job.getProperty(DAM_EVENT_ASSET_PATH) != null) {
String assetPath = (String) job.getProperty(DAM_EVENT_ASSET_PATH);
logger.trace(assetPath);
backupService.trackModification(assetPath);
} else {
logger.trace("Invalid event type. Cannot help.");
}
return JobResult.OK;
}
}

Updating Dropwizard config at runtime

Is it possible to have my app update the config settings at runtime? I can easily expose the settings I want in my UI but is there a way to allow the user to update settings and make them permanent ie save them to the config.yaml file? The only way I can see it to update the file by hand then restart the server which seems a bit limiting.

Yes. It is possible to reload the service classes at runtime.
Dropwizard by itself does not have the way to reload the app, but jersey has.
Jersey uses a container object internally to maintain the running application. Dropwizard uses the ServletContainer class of Jersey to run the application.
How to reload the app without restarting it -
Get a handle to the container used internally by jersey
You can do this by registering a AbstractContainerLifeCycleListener in Dropwizard Environment before starting the app. and implement its onStartup method as below -
In your main method where you start the app -
//getting the container instance
environment.jersey().register(new AbstractContainerLifecycleListener() {
#Override
public void onStartup(Container container) {
//initializing container - which will be used to reload the app
_container = container;
}
});
Add a method to your app to reload the app. It will take in the list of string which are the names of the service classes you want to reload. This method will call the reload method of the container with the new custom DropWizardConfiguration instance.
In your Application class
public static synchronized void reloadApp(List<String> reloadClasses) {
DropwizardResourceConfig dropwizardResourceConfig = new DropwizardResourceConfig();
for (String className : reloadClasses) {
try {
Class<?> serviceClass = Class.forName(className);
dropwizardResourceConfig.registerClasses(serviceClass);
System.out.printf(" + loaded class %s.\n", className);
} catch (ClassNotFoundException ex) {
System.out.printf(" ! class %s not found.\n", className);
}
}
_container.reload(dropwizardResourceConfig);
}
For more details see the example documentation of jersey - jersey example for reload
Consider going through the code and documentation of following files in Dropwizard/Jersey for a better understanding -
Container.java
ContainerLifeCycleListener.java
ServletContainer.java
AbstractContainerLifeCycleListener.java
DropWizardResourceConfig.java
ResourceConfig.java

No.
Yaml file is parsed at startup and given to the application as Configuration object once and for all. I believe you can change the file after that but it wouldn't affect your application until you restart it.
Possible follow up question: Can one restart the service programmatically?
AFAIK, no. I've researched and read the code somewhat for that but couldn't find a way to do that yet. If there is, I'd love to hear that :).

I made a task that reloads the main yaml file (it would be useful if something in the file changes). However, it is not reloading the environment. After researching this, Dropwizard uses a lot of final variables and it's quite hard to reload these on the go, without restarting the app.
class ReloadYAMLTask extends Task {
private String yamlFileName;
ReloadYAMLTask(String yamlFileName) {
super("reloadYaml");
this.yamlFileName = yamlFileName;
}
#Override
public void execute(ImmutableMultimap<String, String> parameters, PrintWriter output) throws Exception {
if (yamlFileName != null) {
ConfigurationFactoryFactory configurationFactoryFactory = new DefaultConfigurationFactoryFactory<ReportingServiceConfiguration>();
ValidatorFactory validatorFactory = Validation.buildDefaultValidatorFactory();
Validator validator = validatorFactory.getValidator();
ObjectMapper objectMapper = Jackson.newObjectMapper();
final ConfigurationFactory<ServiceConfiguration> configurationFactory = configurationFactoryFactory.create(ServiceConfiguration.class, validator, objectMapper, "dw");
File confFile = new File(yamlFileName);
configurationFactory.build(new File(confFile.toURI()));
}
}
}

You can change the configuration in the YAML and read it while your application is running. This will not however restart the server or change any server configurations. You will be able to read any changed custom configurations and use them. For example, you can change the logging level at runtime or reload other custom settings.
My solution -
Define a custom server command. You should use this command to start your application instead of the "server" command.
ArgsServerCommand.java
public class ArgsServerCommand<WC extends WebConfiguration> extends EnvironmentCommand<WC> {
private static final Logger LOGGER = LoggerFactory.getLogger(ArgsServerCommand.class);
private final Class<WC> configurationClass;
private Namespace _namespace;
public static String COMMAND_NAME = "args-server";
public ArgsServerCommand(Application<WC> application) {
super(application, "args-server", "Runs the Dropwizard application as an HTTP server specific to my settings");
this.configurationClass = application.getConfigurationClass();
}
/*
* Since we don't subclass ServerCommand, we need a concrete reference to the configuration
* class.
*/
#Override
protected Class<WC> getConfigurationClass() {
return configurationClass;
}
public Namespace getNamespace() {
return _namespace;
}
#Override
protected void run(Environment environment, Namespace namespace, WC configuration) throws Exception {
_namespace = namespace;
final Server server = configuration.getServerFactory().build(environment);
try {
server.addLifeCycleListener(new LifeCycleListener());
cleanupAsynchronously();
server.start();
} catch (Exception e) {
LOGGER.error("Unable to start server, shutting down", e);
server.stop();
cleanup();
throw e;
}
}
private class LifeCycleListener extends AbstractLifeCycle.AbstractLifeCycleListener {
#Override
public void lifeCycleStopped(LifeCycle event) {
cleanup();
}
}
}
Method to reload in your Application -
_ymlFilePath = null; //class variable
public static boolean reloadConfiguration() throws IOException, ConfigurationException {
boolean reloaded = false;
if (_ymlFilePath == null) {
List<Command> commands = _configurationBootstrap.getCommands();
for (Command command : commands) {
String commandName = command.getName();
if (commandName.equals(ArgsServerCommand.COMMAND_NAME)) {
Namespace namespace = ((ArgsServerCommand) command).getNamespace();
if (namespace != null) {
_ymlFilePath = namespace.getString("file");
}
}
}
}
ConfigurationFactoryFactory configurationFactoryFactory = _configurationBootstrap.getConfigurationFactoryFactory();
ValidatorFactory validatorFactory = _configurationBootstrap.getValidatorFactory();
Validator validator = validatorFactory.getValidator();
ObjectMapper objectMapper = _configurationBootstrap.getObjectMapper();
ConfigurationSourceProvider provider = _configurationBootstrap.getConfigurationSourceProvider();
final ConfigurationFactory<CustomWebConfiguration> configurationFactory = configurationFactoryFactory.create(CustomWebConfiguration.class, validator, objectMapper, "dw");
if (_ymlFilePath != null) {
// Refresh logging level.
CustomWebConfiguration webConfiguration = configurationFactory.build(provider, _ymlFilePath);
LoggingFactory loggingFactory = webConfiguration.getLoggingFactory();
loggingFactory.configure(_configurationBootstrap.getMetricRegistry(), _configurationBootstrap.getApplication().getName());
// Get my defined custom settings
CustomSettings customSettings = webConfiguration.getCustomSettings();
reloaded = true;
}
return reloaded;
}

Although this feature isn't supported out of the box by dropwizard, you're able to accomplish this fairly easy with the tools they give you.
Before I get started, note that this isn't a complete solution for the question asked as it doesn't persist the updated config values to the config.yml. However, this would be easy enough to implement yourself simply by writing to the config file from the application. If anyone would like to write this implementation feel free to open a PR on the example project I've linked below.
Code
Start off with a minimal config:
config.yml
myConfigValue: "hello"
And it's corresponding configuration file:
ExampleConfiguration.java
public class ExampleConfiguration extends Configuration {
private String myConfigValue;
public String getMyConfigValue() {
return myConfigValue;
}
public void setMyConfigValue(String value) {
myConfigValue = value;
}
}
Then create a task which updates the config:
UpdateConfigTask.java
public class UpdateConfigTask extends Task {
ExampleConfiguration config;
public UpdateConfigTask(ExampleConfiguration config) {
super("updateconfig");
this.config = config;
}
#Override
public void execute(Map<String, List<String>> parameters, PrintWriter output) {
config.setMyConfigValue("goodbye");
}
}
Also for demonstration purposes, create a resource which allows you to get the config value:
ConfigResource.java
#Path("/config")
public class ConfigResource {
private final ExampleConfiguration config;
public ConfigResource(ExampleConfiguration config) {
this.config = config;
}
#GET
public Response handleGet() {
return Response.ok().entity(config.getMyConfigValue()).build();
}
}
Finally wire everything up in your application:
ExampleApplication.java (exerpt)
environment.jersey().register(new ConfigResource(configuration));
environment.admin().addTask(new UpdateConfigTask(configuration));
Usage
Start up the application then run:
$ curl 'http://localhost:8080/config'
hello
$ curl -X POST 'http://localhost:8081/tasks/updateconfig'
$ curl 'http://localhost:8080/config'
goodbye
How it works
This works simply by passing the same reference to the constructor of ConfigResource.java and UpdateConfigTask.java. If you aren't familiar with the concept see here:
Is Java "pass-by-reference" or "pass-by-value"?
The linked classes above are to a project I've created which demonstrates this as a complete solution. Here's a link to the project:
scottg489/dropwizard-runtime-config-example
Footnote: I haven't verified this works with the built in configuration. However, the dropwizard Configuration class which you need to extend for your own configuration does have various "setters" for internal configuration, but it may not be safe to update those outside of run().
Disclaimer: The project I've linked here was created by me.

Create OSGI Service which requires user parameter

I'm just starting to learn osgi. Need create application, which provide Search Service. Search Service depends on the platform (SearchServiceLinux, SearchServiceAndroid, SearchServiceXXX ...). Also search service depends on a parameter that the user enters. Parameter is mandatory.
My Search Service Consumer (Then user set the parameter i create new instance of SearchService):
#Component(immediate = true, publicFactory = false)
#Provides(specifications = {TestConsumer.class})
#Instantiate
public class TestConsumer {
#Requires(filter = "(factory.name=package.ISearchService)")
private Factory mFactory;
private ComponentInstance mSearchComponentInstance;
...
public void userSetParameter(String pParameter) {
Properties lProperties = new Properties();
lProperties.put("instance.name", mFactory.getName() + "-" + pParameter);
lProperties.put("Parameter", pParameter);
if (mSearchComponentInstance != null) {
mSearchComponentInstance.dispose();
}
try {
mSearchComponentInstance = mFactory.createComponentInstance(lProperties);
} catch (UnacceptableConfiguration e) {
e.printStackTrace();
} catch (MissingHandlerException e) {
e.printStackTrace();
} catch (ConfigurationException e) {
e.printStackTrace();
}
}
My Search Service:
#Component
#Provides(specifications = {ISearchService.class}, strategy = "SINGLETON")
public class TestServise implements ISearchService{
#ServiceProperty(name = "Parameter", mandatory = true)
private int mParameter;
...
Questions:
1) Is this true structure of the program? #ServiceProperty or #Property more preferable in this case? What is the best practice for OSGI Service which requires parameters from user input? Is it possible to reform the structure of the consumer to use:
#Requires (filter = "need filter for SearchService with Parameter=XXX or create this service")
ISearchService mSearchService;
2) Can be applied in this situation iPOJO Event Admin Handlers?
Consumer:
#Publishes(name = "p1", topics = "userChangeParameter")
private Publisher mPublisher;
public void userChangeParameter(String pParameter) {
Properties lProperties = new Properties();
lProperties.put("Parameter", pParameter);
mPublisher.send(lProperties);
}
Search Service:
#Subscriber(name = "s0", topics = "foo")
public void subscriber(Event pEvent) {
System.out.println("Subscriber : " + pEvent.getProperty("Parameter"));
}
3) What is the best structure to create a service that depends on the parameters entered by the user? Maybe the problem is solved easily by using Apache Felix Subprojects?
I use apache felix 4.2.1.

I would create a service like this:
#Component(
metatype = false)
#SlingServlet(
paths = { "/bin/test/service" }, methods = { "POST" }, extensions = { "json" },
selectors = { "selector1", "selector2"}, generateComponent = false)
public class TestConsumer extends SlingAllMethodsServlet {
//inject all the services here like SearchServiceLinux, etc.
#Reference
private SearchServiceLinux searchServiceLinux;
}
You can use this service like
http://localhost/bin/test/service.seletor1.html
Now based on selector you can decide which class will handle the request means you can decide that seletor1 will be handled by class X and selector2 will be handled by class Y
If parameters are mandatory then I would recommend you to accept only POST on this service and make sure you provide search parameters in POST say parameter name is searchParam, so based on selector you can decide the handler and you can pass searchParam to this handler to generate search results.
Hope this helps.