CEvbClientApp -- Framework event builder client application.


#include <CEVBClientApp.h>
class   CEVBClientApp {
  virtual void initialize();
          virtual  = 0 bool dataReady(int ms);
          virtual  = 0 void getEvents();
          virtual void shutdown();


CEvbClientApp is an abstract base class for applications that use the Event builder data source application framework. This class conatains an interface definition that consists of some methods that are pure virtual and others for which there is a default implementation.

See METHODS below for a description of the base class methods as well as the interface methods. CEVBClientFramework for more information about the methods that are available for your custom code to interface with the remainder of the framework.



The base class constructor is responsible for registering objects that are constructed with the framework. Note that all objects of this type that are created will be registered allowing for super sources to be created.

virtual void initialize();

This method is invoked by the framework exactly once. Almost all of your one-time intialization should be performed here. The base class provides an empty default implementation so that you do not need to override this method if you do not require any one-time initialization.

virtual = 0 bool dataReady(int ms);

Called to determine if the data source you are managing has data to process. ms is an estimate of the maximum amount of time you should block prior to returning.

Return true if there is data to be read (in which case getEvents will soon be called), otherwise return false.

virtual = 0 void getEvents();

Called to read events from the data source and submit them to the evenbuilder via one or more calls to CEVBClientFramework::submitFragmentList.

virtual void shutdown();

Called when the client is being properly shutdown. You should release any resources that were dynamically allocated by your event source. This is especially important for resources that involve inter-process communications so that they don' have to close down via a timeout.


Two types are often used by event fragment sources: ClientEventFragment represents the metadata for an event fragment along with a pointer to the fragment itself. CEVBEventList is a list of ClietEventFragment objects. It is actually a specific std::list and has all of the methods of that class.

The ClientEventFragment type is a struct with the following members:

uint64_t s_timestamp;

The event fragment timestamp. For event ordering/building to work, the timestamp for all sources must come from a common timebase and be synchronized.

uint32_t s_sourceId;

Identifies the source. In the output of both the event orderer and the builder, each fragment will be tagged with its source id. Source Ids:

  • Should be unique from source to source.

  • Should produce fragments that are time ordered.

  • Each have their own fragment queue. You therefore do not need to order fragments across event source only within sources.

uint32_t s_size;

The number of bytes in the fragment data.

void* s_payload;

A pointer to the event fragment.