4. Building an RMI Application — RMI User Guide

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# 4. Building an RMI Application

## 4.1. About RMI Applications

The process of building an Vortex OpenSplice RMI application is shown in Steps Building Applications with RMI below. The different steps are described in the following subsections.

Steps Building Applications with RMI

## 4.2. Services description

The first step in building an RMI application is the definition of its provided services in terms of interfaces. The application interfaces should be declared using the OMG IDL language. The operations parameters can be either of basic (`short`, `long`, ...) or complex (`struct`, `sequence`, `string`, ...) types. However, the following restrictions should be respected:

- the `Any` and the `valuetype` IDL types are not supported because they are not supported by the underlying DDS DCPS layer. `Union` type is also not supported.
- Exceptions are not supported at this time.
- Each interface must extend `DDS_RMI::Services` base interface to indicate that it is invocable over DDS. This interface is defined in the file `dds_rmi.idl`, which must be included.
- Each interface must be declared `local’.
- Oneway operations are supported. The semantics of oneway operations is the same as for the OMG CORBA interfaces. A oneway operation must not contain any output parameter and must return a void type.

The following IDL snippet shows an example of a service data description:

    #include "dds_rmi.idl"
    module HelloWorld
    {
      // interface definition
    local interface HelloService : ::DDS_RMI::Services
    {
      string greet();
    };
    };

## 4.3. QoS policies description

The Vortex OpenSplice RMI module provides the ability to tune the quality of service of the services invocations (requests and/or replies), if needed, by setting the underlying DDS QoS policies. By default, the DDS RMI module uses the default values of the DDS QoS policies except for the reliability QoS policy which is set to `RELIABLE`.

If needed, the application designer can define the QoS policies to be set on the invocations in an XML file. This file must respect the XML schema given in QoS policies XML schema.

Note that setting the DDS QoS policies requires a good knowledge of the rules for mapping the specified interfaces onto the DDS topics description (please refer to RMI Interface to DDS topics mapping rules).

The following XML snippet shows an example:

    <?xml version="1.0" encoding="ISO-8859-1" ?>
    <dcps xmlns="http://www.omg.org/dds/"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.omg.org/dds/DCPS.xsd">

    <domain id="">
      <topic name="greet_req"
    idltype="::HelloWorld::HelloService::greet_request" idlfile="">

      <topic_qos>
      <destinationOrderQosPolicy>
        <destinationOrderKind>
          BY_SOURCE_TIMESTAMP_DESTINATIONORDER_QOS
        </destinationOrderKind>
      </destinationOrderQosPolicy>

      <durabilityQosPolicy>
        <durabilityKind>
          PERSISTENT_DURABILITY_QOS
        </durabilityKind>
      </durabilityQosPolicy>

      <latencyBudgetQosPolicy>
        <duration>
          <nanosec>10000000</nanosec>
          <sec>0</sec>
        </duration>
      </latencyBudgetQosPolicy>

      <reliabilityQosPolicy>
        <duration>
          <nanosec>100000000</nanosec>
          <sec>0</sec>
        </duration>
      <reliabilityKind>
        RELIABLE_RELIABILITY_QOS
      </reliabilityKind>
      </reliabilityQosPolicy>

      </topic_qos>

      </topic>

    </domain>
    </dcps>

This example specifies the QoS policies to be applied on the topic invocation request of the `greet` operation of the interface `HelloWorld::HelloService`. Note that the invocation request topic is named `greet_req` and its IDL type is `HelloWorld::HelloService::greet_request`.

## 4.4. RMI compilation

Once the application has defined its services and (optionally) its QoS settings, these definitions are compiled to generate type-specific code for the application services invocation.

The RMI compilation is done using the `rmipp` pre-processor applied on the interfaces definition file and the QoS file if it exists. The `rmipp` usage is:

    rmipp [-l (java | c++)] [-I <path>] [-d <directory>] [-topics
    <qos_file>] [-P dll_macro_name[,<header-file>]] <interfaces_file>

The parameters are:

-l (java | c++)
  Define the target language. The C++ language is the default.
-I <path>
  Define the include path directives.
-d <directory>
  Define the location to place the generated files.
-topics <qos_file>
  Define the XML file including the QoS policies settings.
-P dll_macro_name[,<header-file>]
  Only applicable to C and C++. Sets export macro that will be prefixed to all functions in the generated code. This allows creating DLLs from generated code. Optionally a header file can be given that will be included in each generated file.
<interfaces_file>
  The IDL file including the interfaces definition.

The `rmipp` compilation will generate a set of Java or C++ source files as well as an IDL file including the mapping of the provided interfaces onto the DDS topics. The generated IDL file name is the interfaces file name with “`_topics`” concatenated.

`Rmipp` follows the mapping rules described in Language mapping for Vortex OpenSplice RMI.

Example usage:

    rmipp -d generated HelloService.idl

The generated directory will include:

> `HelloService_topics.idl`
> `HelloService_Interface.h`
> `HelloService_Interface.cpp`
> `HelloService_InterfaceProxy.h`
> `HelloService_InterfaceProxy.cpp`

In addition, the `rmipp` compiler performs a DDS compilation to generate the DDS/DCPS code that is required to support the requests/replies transport over DDS.

## 4.5. Application implementation

As mentioned before, the target applications have a client/server design. A typical application includes a server part that implements the provided interfaces, and a client part that invokes these interfaces. This section describes the programming model of both parts.

### 4.5.1. Runtime starting and stopping

Any DDS RMI application process must initialize the RMI runtime prior to any other operation, regardless of whether it is a client and/or a server process. The runtime initialization sets up the underlying DDS infrastructure and configures it to make the services invocable and the clients capable of invoking the services. It is also important to stop the runtime when the application is no longer using RMI.

The following code snippets show the runtime initialisation and stopping procedure in C++ and Java.

RMI runtime starting and stopping in C++

    01  #include "ddsrmi.hpp"
    02
    03  using namespace org::opensplice::DDS_RMI;
    04
    05  int main (int argc, char * argv [])
    06  {
    07    CRuntime_ref runtime = CRuntime::getDefaultRuntime();
    08    if (runtime.get() == NULL)
    09    {
    10      std::cout << "Failed to get the Runtime " << std::endl;
    11      exit(1);
    12    }
    13
    14    //starting the runtime
    15    bool result = runtime->start(argc, argv);
    16    if (result !=true)
    17    {
    18      std::cout << "Failed to start the Runtime " << std::endl;
    19      exit(1);
    20    }
    21    ...
    22
    23    //stopping the runtime
    24    result = runtime->stop();
    25    if (result !=true)
    26    {
    27      std::cout << "Failed to stop the Runtime " << std::endl;
    28      exit(1);
    29    }
    30  }

Comments below refer to line numbers in the sample code above:

1 Include the OpenSplice RMI library header file.
  Any OpenSplice RMI application should include this file.

3 Declare the usage of the OpenSplice RMI library namespace.

7-12 Get the default DDS runtime.
  This selects the default DDS domain as the data space where all subsequent RMI requests and replies will be exchanged.
15-20 Initialize the created runtime.
  This creates all the needed DDS entities. A set of configuration options can be passed to the `start` operation via `argc` and `argv` parameters. This latter is a string array including possible option names and values, and `argc` is the length of this array. Note that these parameters are typically the same parameters that were passed to the main program so that the RMI options can be specified on the command line, each following the format ‘`--option=value`‘. All of the supported options are described in the section RMI Runtime Configuration Options.
24-28 Stop the created runtime.
  This removes all the created DDS entities and releases the RMI-allocated resources. It is strongly recommended to stop the runtime when it no longer needed.

The Java code below works in a similar way.

RMI runtime starting and stopping in Java

    import org.opensplice.DDS_RMI;

    static void main (String[] args)
    {

      CRuntime runtime = CRuntime.getDefaultRuntime();
      if(null == runtime)
      {
        System.out.println();
        System.exit(1);
      }

      //starting the runtime
      boolean result = runtime.start(args);
      if(!result)
      {
        System.out.println("Failed to start the Runtime") ;
        System.exit(1);
      }
      ...
      //stopping the runtime
      result = runtime.stop();
      if(!result)
      {
        System.out.println("Failed to stop the Runtime") ;
        System.exit(1);
      }
    }

### 4.5.2. Server programming model

At the server side of the application, each provided interface should be implemented, then instantiated and finally registered to be invocable via Vortex OpenSplice.

To define an implementation, the application developer must write an implementation class including public methods corresponding to the operations of the related IDL interface. The `rmipp` compilation generates for each interface a skeleton class, named `::DDS_RMI::HelloWorld::HelloServiceInterface`, that must be extended by the application-supplied implementation class. The language mapping rules of the RMI IDL interfaces are given in Language mapping for Vortex OpenSplice RMI.

To make an interface invocable over DDS, it must be registered within the RMI framework, then activated. The registration process requires the following information:

- the implementation class object
- the server name, as well as a unique id identifying that interface inside the server.

The services activation makes the RMI runtime wait for incoming requests for all the registered services.

The following code snippets show the server programming model in C++ and Java.

C++ RMI interface implementation

    class HelloService_impl :
          public virtual DDS_RMI::HelloWorld::HelloServiceInterface
    {
    public:
        HelloService_impl();
       ~ HelloService_impl();

       virtual DDS::String greet ();
    }

Java RMI interface implementation

    public class HelloService_impl :
    DDS_RMI.HelloWorld.myInterfaceInterface {
       public String greet ()
       {
          // operation implementation
       }
    }

C++ RMI server

    01   #include “ddsrmi.hpp”
    02   #include “HelloService_Interface.hpp”
    03
    04   using namespace org::opensplice::DDS_RMI;
    05
    06   int main (int argc, char * argv [])
    07   {
    08
    09      // Runtime starting
    10      ...
    11
    12      // implementation class instantiation
    13      shared_ptr<HelloService_impl> impl (new HelloService_impl());
    14
    15      //interface registration
    16      bool res = DDS_Service::register_interface<
    16      ::DDS_RMI::HelloWorld::HelloServiceInterface, HelloService_impl>
    17      (
    18            impl, //implementation class
    19            “HelloServer”, // server name
    20            1 // unique server id
    21       );
    22
    23      if(!res)
    24      {
    25          std::cout << "Failed to register the
    25                        HelloWorld::HelloService interface") ;
    26          System.exit(1);
    27      }
    28      //services activation
    29      runtime->run()
    30      // Runtime stopping
    31      ...
    32   }

Comments below refer to line numbers in the sample code above:

1-2 Include the OpenSplice RMI library header file as well as the generated interface skeleton header file.

4 Declare the usage of the OpenSplice RMI library namespace.

10 Start the DDS runtime.

13 Instantiate the implementation class of the `HelloService` interface and assign it to a smart pointer.
  The OpenSplice RMI library provides an implementation of smart pointers via the `shared_ptr` template class.
16-27 Register the `HelloService` interface in the default DDS domain.
  The `register_interface` function is a template function requiring the interface skeleton class and the interface implementation class as template parameters.
28 Activates all the registered services including the `HelloServer` service.
  This is a blocking call that makes the server runtime wait for incoming requests. To shut down the server runtime the `shutdown()` operation must be called.

31 Stop the DDS runtime.

The Java code below works in a similar way.

Java RMI server

    static void main (String[] args)
    {

       // Runtime starting
       ...

       // implementation class instanciation
       HelloService_impl impl = new HelloService_impl();

       // interface registration
       boolean res = org.opensplice.DDS_RMI.DDS_Service.register_interface
       (
             impl, // implementation class
             “HelloServer”, // server name
             1, // unique server id
             DDS_RMI.HelloWorld.HelloServiceInterface.class //Interface java Class
       );

       if(!res)
       {
           System.out.println("Failed to register the
                               HelloWorld::HelloService interface") ;
           System.exit(1);
       }
    runtime.run();
       // Runtime stopping
       ...
    }

### 4.5.3. Client programming model

As mentioned before, OpenSplice RMI supports synchronous, asynchronous and oneway invocation modes. The following subsections present the synchronous and asynchronous programming model. The oneway programming model is similar to the synchronous one but, of course, with a different behaviour.

#### 4.5.3.1. Synchronous invocation mode

The client part of the RMI application is as simple as calling a local class. Note that these calls block until the server-side responds or an internal timeout expires. Typically, in case of failure, the call will block until the timeout expiration. This timeout value is set by default to 10 minutes, but it may be configured via the interface proxy object. This object is a generated object, named `::DDS_RMI::HelloWorld::HelloServiceInterfaceProxy`, that is the local representative of the RMI interface. This object is mainly used to call the RMI services, as shown in the following client code examples.

C++ RMI client

    01 #include “ddsrmi.hpp”
    02 #include “HelloService_InterfaceProxy.hpp”
    03
    04 using namespace org::opensplice::DDS_RMI;
    05
    06 int main (int argc, char * argv [])
    07 {
    08
    09   // Runtime starting
    10   ...
    11
    12   // Getting the interface proxy
    13   shared_ptr<::DDS_RMI::HelloWorld::HelloServiceInterfaceProxy> proxy ;
    14   bool ret = DDS_Service::getServerProxy<
    14              ::DDS_RMI::HelloWorld::HelloServiceInterfaceProxy>
    15     (
    16       “HelloServer”, //server name
    17       1, //unique proxy instance id
    18       proxy  // proxy reference
    19     );
    20
    21   // Calling the services
    22   proxy->greet();
    23
    24   // Runtime stopping
    25   ...
    26
    27 }

Comments below refer to line numbers in the sample code above:

1-2 Include the RMI library header file as well as the generated interface proxy header file.

4 Declare the usage of the OpenSplice RMI library namespace.

10 Start the DDS runtime.

13 Declare a smart pointer of the HelloService interface proxy type.

13-19 Get the HelloServer service proxy.
  The `getServerProxy` function is a template function requiring the proxy class type as a template parameter. This function accepts the service name, a proxy instance id and the smart pointer to the proxy object as parameters. In case of success, the smart pointer is set to the created proxy object. The proxy instance id is a unique identifier that refers to the created proxy. It is important to ensure the uniqueness of the identifiers of all the proxies of the same service. If the client application intends to use the same proxy in different threads, the MultiThreaded mode must be set (see MultiThreaded Client later in this chapter). If the requested service is not found, the `getServerProxy` operation will raise an `org::opensplice::DDS_RMI::SERVICE_NOT_FOUND` exception.

22 Invoke the greet operation synchronously using the created proxy.

25 Stop the runtime.

The Java code below works in a similar way.

Java RMI client

    import org.opensplice.DDS_RMI.*;

    static void main (String[] args) {

      // Runtime starting
      ...

      // Getting the interface proxy
      try {
      DDS_RMI.HelloWorld.HelloServiceInterfaceProxy proxy =
        DDS_Service.getServerProxy (
          "HelloServer", //server name
          1, //unique proxy instance id
           DDS_RMI.HelloWorld.HelloServiceInterfaceProxy.class // proxy java Class
        );

      // Calling the services
      proxy.greet();
      } catch (SERVICE_NOT_FOUND e) {
      // error
      }
      // Runtime stopping
      ...

    }

#### 4.5.3.2. Asynchronous invocation mode

To invoke asynchronously a given non-oneway operation, such as the `greet` operation in the examples shown here, the client application must:

- Implement a specific reply handler class to handle the operation out/inout/return parameters if any. This handler must extend a base reply handler class that is generated for each operation and implement the `greetReply` callback function or method whose parameters are the out/inout/return parameters of the related IDL operation.
- Use the generated asynchronous function or method that maps to the IDL operation whose name is the concatenation of ‘`async_`’ and the IDL operation name. This operation is a void operation that accepts only the `in` and `inout` IDL parameters, in addition to the eference of the implemented reply handler.

Note that the reply handler class is not re-entrant in the current implementation. It cannot handle concurrent replies. It means that if two successive asynchronous calls are made with the same reply handler instance, this latter will reject the second reply if it has not finished dispatching the first one. In this case the asynchronous call will raise a `BAD_PARAM` exception.

  IMPORTANT: It is strongly recommended not to mix synchronous and asynchronous calls of the same operation without proper synchronization. The application should ensure that the asynchronous call has received its reply before requesting a synchronous one.

C++ RMI Client with asynchronous invocation

    01   #include "ddsrmi.hpp"
    02   #include "HelloService_InterfaceProxy.hpp"
    03
    04   using namespace org::opensplice::DDS_RMI;
    05
    06   /**
    07   * Reply Handler of the 'async_greet' operation
    08   *
    09   */
    10   class MyGreetReplyHandler :
    11      public virtual   HelloWorld_HelloService_greet_Reply_Handler
    12   {
    13      void greet_Reply(DDS::String ret)
    14      {
    15           std::cout << "Reply received: " << ret << std::endl;
    16      }
    17   }
    18
    19   int main (int argc, char * argv [])
    20   {
    21
    22   // Runtime starting
    23      ...
    24
    25   // Getting the interface proxy
    26   shared_ptr<::DDS_RMI::HelloWorld::HelloServiceInterfaceProxy> proxy ;
    27   bool ret = DDS_Service::getServerProxy<
    27              ::DDS_RMI::HelloWorld::HelloServiceInterfaceProxy>
    28      (
    29        "HelloServer", //server name
    30        1, // proxy instance id
    31        proxy  // proxy reference
    32      );
    33
    34   // instantiating a reply handler
    35   MyGreetReplyHandler handler;
    36
    37   // Calling the services asynchronously
    38   proxy->async_greet(&handler);
    39   ...
    40
    41   // Runtime stopping
    42   ...
    43
    44   }

Comments below refer to line numbers in the sample code above:

10-16 Provide the implementation class of the `greet` operation reply handler.

21 Start the DDS runtime.

24-31 Get the `HelloServer` service proxy as for the synchronous mode.

34 Instantiate the `greet` reply handler class.

37 Invoke the `async_greet()` operation by providing the reply handler.
  This call is a non-blocking call. The application steps immediately to the next instruction. The invocation reply will be delivered to the application by invoking the `greet_Reply` operation of the reply handler. Note that this operation will be invoked in a middleware-provided thread.
41 Stop the runtime.
  Note that some synchronization may be needed to avoid exiting before the `async_greet` reply is delivered to the application.

The Java code below works in a similar way.

Java RMI Client with asynchronous invocation

    import org.opensplice.DDS_RMI.*;

    /**
         * Reply Handler of the 'async_greet' operation
         *
         */
        class MyGreetReplyHandler extends
              DDS_RMI.HelloWorld.HelloServiceInterfaceProxy.greet_Reply_Handler {
            public void greet_Reply(String ret) {
                System.out.println("async_greet returns: " + ret);
            }
        };

    static void main (String[] args) {

       // Runtime starting
       ...

      try {
       // Getting the interface proxy
       DDS_RMI.HelloWorld.HelloServiceInterfaceProxy proxy =
          DDS_Service.getServerProxy (
            "HelloServer", //server name
            1, //server instance id
             DDS_RMI.HelloWorld.HelloServiceInterfaceProxy.class // proxy java Class
          );

       // Calling the services asynchronously
       proxy.asynch_greet();
      } catch(SERVICE_NOT_FOUND e) {
        System.out.println("'HelloServer' service not found !");
      }

       // Runtime stopping
       ...

    }

#### 4.5.3.3. MultiThreaded Client

The default threading model of a client application is single threaded. It means that, by default, a service proxy may not be used by multiple concurrent threads to perform service invocations. To enable or disable the multithreaded mode for clients, a configuration option must be specified in the command line as follows:

> `--RMIClientThreadingModel=[ST|MT]`

## 4.6. Using a specific DDS domain

Using the default RMI CRuntime implies that all the RMI invocations will be performed within the default DDS domain. The default domain id is the one specified by the current Vortex OpenSplice configuration, specifically in the Domain Service section of the related XML file. The default Vortex OpenSplice configuration files set the `domain id` to `0`. For more information on configuring Vortex OpenSplice please refer to the Vortex OpenSplice Deployment Guide.

If the RMI application operates with a user-defined domain id, using the default CRuntime enables RMI interactions within that domain. In case of an application operating in multiple domains, it should create a CRuntime object for the targeted domain id and get a `DDS_ServiceInterface` object from that CRuntime. The `DDS_ServiceInterface` object provides all the convenient methods for server applications to register/unregister services and for client applications to get service proxies on the relevant domain id. These methods are the same as the `DDS_Service` object ones. The following code snippets show this in C++ and Java.

Getting DDS_ServiceInterface in C++

    // Getting a CRuntime on my specific domain
    CRuntime_ref runtime = CRuntime::getRuntime(my_domain_id);
    // Getting a DDS_ServiceInterface object
    DDS_ServiceInterface_ref dds_service = runtime->getDDS_ServiceInterface();

Getting DDS_ServiceInterface in Java

    // Getting a CRuntime on my specific domain
    CRuntime runtime = CRuntime.getRuntime(my_domain_id);
    // Getting a DDS_ServiceInterface object
    DDS_ServiceInterface dds_service = runtime.getDDS_ServiceInterface();

## 4.7. Server Threading and Scheduling policies

OpenSplice RMI allows configuration of the threading and the scheduling models of the RMI server applications by enabling a set of policies that control how the server allocates threads to handle service invocations and how these threads are scheduled with regard to the others. Hence developers may enhance the responsiveness of their services by choosing a multi-threaded execution model, or may protect a non-thread-safe service implementation by choosing a single thread execution model.

### 4.7.1. Threading policies

OpenSplice RMI provides three threading policies that apply on a single RMI runtime at the server side. The RMI runtime uses a thread pool that hosts a number of threads to execute the services incoming requests. This number defines the thread pool size and depends on the specified threading policy.

1 – Single Thread (ST) policy
  This policy allocates a single thread to process all the services’ incoming requests within the server process. The requests are processed one by one in the order that they are received. It guarantees that no two threads will execute concurrently the different services calls within that server. In this case, the RMI runtime creates a single thread pool. This policy is the default threading policy. The ST policy ensures thread safety to all the services within the server process, but with the drawback that services with long-running tasks will block the others.
2 – Thread Per Service (TPS) policy
  This policy allocates a single thread to each service, up to the number specified as the thread pool size. All the requests coming to one service are processed in sequence by a single thread borrowed from the thread pool, but different services requests are processed in parallel, within the limit of the thread pool size. The thread pool size is defined by the user application. The TPS policy ensures that services having long-running requests won’t block the others, but concurrent calls are not possible for one single service.
3 – Multi Thread (MT) policy
  This policy allows for a full multi-threaded environment. All the incoming requests are processed concurrently in different threads whatever the targeted services, within the limit of the thread pool size. The service implementation should take care of that and ensure thread safety. The thread pool size is user-defined.

#### 4.7.1.1. Scheduling policies

These policies specify the scheduling parameters that will be used for the threads created by the RMI runtime for a RMI server.

A RMI scheduling policy is defined by a scheduling priority and a scheduling class. The scheduling priority specifies the priority that will be assigned to all the threads that are spawned by the RMI runtime. The scheduling class may be `SCHEDULE_DEFAULT`, `SCHEDULE_TIMESHARING`, or `SCHEDULE_REALTIME`. These scheduling classes depend on the underlying operating system. A `SCHEDULE_DEFAULT` class is the default OS scheduling algorithm.

In general, the Timesharing class attempts to distribute the processor resources fairly among the threads. In a Realtime class a thread normally runs until completion but can be pre-empted by higher-priority threads. Both Timesharing and Realtime scheduling classes are priority-based, so the scheduling priority is meaningful for both classes.

  Note that some scheduling classes may not be supported by the underlying operating system, or that you may need special privileges to select particular settings.
  Note that the Java platform does not define a scheduling model for threads but defers to the underlying thread implementation. As a result, only the scheduling priority is usable for the Java RMI applications. In fact, there is a notion of priority in the Java threading model, but this is only a hint to the scheduler. The way in which the JVM maps these hints to the underlying OS scheduler varies from JVM to JVM and even from platform to platform for a given JVM.

#### 4.7.1.2. Service priority

OpenSplice RMI allows priorities to be assigned to the services registered in a RMI runtime within a server process. It defines the business importance of each service relative to the others. It allows incoming requests to be handled in order of priority if not enough threads are available to handle them concurrently. The service priority is exploited by the OpenSplice RMI framework to decide which service request a thread should be assigned to first, whereas the scheduling priority is exploited by the OS scheduler itself to decide which thread should run first.

By default, each RMI service has priority set to `0`.

#### 4.7.1.3. Programming model

Threading and scheduling policies may be passed either by command line, or programmatically at runtime. The command line options are described in RMI Runtime Configuration Options; this section shows the related APIs only.

Setting the threading/sceduling policies in Java

    01  // getting and starting the default runtime
    02  CRuntime runtime = Cruntime.getDefaultRuntime();
    03  boolean res = runtime.start(argv);
    04
    05  //setting a MT threading policy with a thread pool size set to 5
    06  ServerThreadingPolicy t_policy = new  ServerThreadingPolicy
    06                                   (ThreadingPolicyKind.MT, 5);
    07  runtime.setServerThreadingPolicy(t_policy);
    08
    09  // setting a scheduling priority and keeping the scheduling
    10  // class to the default
    11  SchedulingPolicy s_policy = runtime.getServerSchedulingPolicy();
    12  s_policy.schedulingPriority = 10;
    13  runtime.setServerSchedulingPolicy(s_policy);
    14
    15  //registering a set of services
    16  HelloService_impl impl = new HelloService_impl();
    17  res  = DDS_Service.register_interface(impl, "HelloServer",1,
    18         DDS_RMI.HelloWorld.HelloServiceInterface.class);
    19  // registering other services
    20
    21  // making HelloServer service the highest priority service
    22  impl.setPriority(2);
    23
    24  //running the runtime
    25  runtime.run();

  Note that setting the thread pool size on java is done asynchronously. This means that there could be more server threads (and thus parallel calls) then expected when reducing the thread pool size.

Setting the threading/sceduling policies in C++

    01  // getting and starting the default runtime
    02  CRuntime_ref runtime = Cruntime::getDefaultRuntime();
    03  bool res = runtime.start(argc, argv);
    04
    05  //setting a MT threading policy with a thread pool size set to 5
    06  ServerThreadingPolicy t_policy = runtime->getServerThreadingPolicy();
    06  t_policy.kind = MT;
    07  t_policy.threadPoolSize = 5;
    08  runtime->setServerThreadingPolicy(t_policy);
    09
    10  // setting a scheduling priority and keeping the scheduling
    11  // class to the default
    12  SchedulingPolicy s_policy = runtime->getServerSchedulingPolicy();
    13  s_policy.schedulingPriority = 10;
    14  runtime.setServerSchedulingPolicy(s_policy);
    15
    16  //registering a set of services
    17  shared_ptr<HelloService_impl> impl (new HelloService_impl());
    18  res  = DDS_Service::register_interface<DDS_RMI::HelloWorld::HelloServiceInterface,
    19         HelloService_impl> (impl, "HelloServer",1);
    20  // registering other services
    21
    22  // making HelloServer service the highest priority service
    23  impl->set_priority(2);
    24
    25  //running the runtime
    26  runtime->run();

  Note that the threading policy may only be changed as long as the runtime is not run. Once run, only the thread pool size may be changed.

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