INFOREPO_PERSISTENCE

Terminology:

Upstream: Business logic layer. Here its the DCPSInfo_i object
Downstream: Different persistence strategies e.g. file persistence
 , federation persistence. The downstream API is in Updater.h

Bridge: The layer bridging the upstream and downstream.
 Here its the UpdateManager.


Initialization:

Upon startup both the downstream and the upstream layers have
to discover the UpdateManager and register with it. Since the UpdateManager is
a service object the discovery is a one-liner

  um_ = ACE_Dynamic_Service<UpdateManager>::instance ("UpdateManager");

Upstream-UpdateManager is a one-to-one relation while the
UpdateManager-downstream is a one-to-many relation. So multiple updaters
(Updater implementers) can be registered simultaneously. The API for
adding updaters is,

  void UpdateManager::add (Updater* updater);

and removal is:

  void UpdateManager::remove (const Updater* updater);

Persistence mechanism:
The upstream deals only with the UpdateManager. The UpdateManager has an
API similar to the Updaters. The UpdateManager class defines the common
data transmission structures. Broadly there is API for adding updates,

  void UpdateManager::add (const UTopic& topic);
  void UpdateManager::add (const UParticipant& participant);

  template <typename UA>
  void UpdateManager::add (const UA& actor);

removing updates:

  void UpdateManager::remove (const IdType& id);

These get mapped to Updater API's:

  virtual void Updater::add(const UpdateManager::DTopic& topic) = 0;
  virtual void Updater::add(const UpdateManager::DParticipant& participant) = 0;
  virtual void Updater::add(const UpdateManager::DActor& actor) = 0;
  virtual void Updater::remove (const IdType& id) = 0;


Image Update:
The upstream requests an image update via:

  void UpdateManager::requestImage (void);

which gets mapped to:

  virtual void Updater::requestImage (void) = 0;

The Updaters get the request in the same thread as the Upstream request. The
downstream can make the update in the same thread (which will make the call
synchronous) or in a different thread (asynchronous). The API for pushing
the image is:

  void UpdateManager::pushImage (const DImage& image);