Subscribing

The SDK provides various options for subscribing to a project.

The steps involved in subscribing to data using the SDK are:

1. Create a NetEspSubscriber from a previously connected NetEspProject instance.
2. Subscribe to one or more streams. Call int32_t NetEspSubscriber::subscribe_stream (NetEspStream^ stream, NetEspError^ error ) for each stream you are connecting to.
3. In direct access mode, retrieve events using NetEspSubscriber.get_next_event(). In callback and select access modes, the event is generated by the SDK and passed back to user code.
4. For data events, retrieve NetEspMessageReader. This encapsulates a single message from the ESP project. It may consist of a single data row or a block with multiple data rows.
5. Retrieve one or more NetEspRowReader. Use the methods in NetEspRowReader to read in individual fields.

• Subscribing to a Stream in Callback Mode
  Subscribing in callback mode is a multistep process that involves creating a subscriber and callback registry, connecting to the subscriber, and then subscribing to a stream.
• Working Example
  The previous sample code on subscribing is provided for illustration purposes, but does not comprise a full, working example.
• Subscribing with Guaranteed Delivery
  Use guaranteed delivery (GD) to ensure that events are still delivered to the subscriber if the connection is temporarily lost or the server is restarted.