Update README of EventHub

sdk/eventhub/azure-eventhubs/README.md

@@ -1,16 +1,13 @@
 # Azure Event Hubs client library for Python
 
-Azure Event Hubs is a big data streaming platform and event ingestion service. It can receive and process millions of events per second.
+Azure Event Hubs is a highly scalable publish-subscribe service that can ingest millions of events per second and stream them to multiple consumers. This lets you process and analyze the massive amounts of data produced by your connected devices and applications. Once Event Hubs has collected the data, you can retrieve, transform, and store it by using any real-time analytics provider or with batching/storage adapters. If you would like to know more about Azure Event Hubs, you may wish to review: [What is Event Hubs](https://docs.microsoft.com/en-us/azure/event-hubs/event-hubs-about)?
 
-Use the Event Hubs client library for Python to:
+The Azure Event Hubs client library allows for publishing and consuming of Azure Event Hubs events and may be used to:
 
-- Publish events to the Event Hubs service through a producer.
-- Read events from the Event Hubs service through a consumer.
-
-On Python 3.5.3 and above, it also includes:
-
-- An async producer and consumer that supports async/await methods.
-- An Event Processor Host module that manages the distribution of partition readers.
+- Emit telemetry about your application for business intelligence and diagnostic purposes.
+- Publish facts about the state of your application which interested parties may observe and use as a trigger for taking action.
+- Observe interesting operations and interactions happening within your business or other ecosystem, allowing loosely coupled systems to interact without the need to bind them together.
+- Receive events from one or more publishers, transform them to better meet the needs of your ecosystem, then publish the transformed events to a new stream for consumers to observe.
 
 [Source code](https://github.com/Azure/azure-sdk-for-python/tree/master/sdk/eventhub/azure-eventhubs) | [Package (PyPi)](https://pypi.org/project/azure-eventhub/) | [API reference documentation](https://docs.microsoft.com/python/api/azure-eventhub) | [Product documentation](https://docs.microsoft.com/en-ca/azure/event-hubs/)
 
@@ -56,15 +53,17 @@ client = EventHubClient.from_connection_string(connection_str)
 
 # Key concepts
 
-- **Namespace:** An Event Hubs namespace provides a unique scoping container, referenced by its fully qualified domain name, in which you create one or more event hubs or Kafka topics.
+- An **Event Hub client** is the primary interface for developers interacting with the Event Hubs client library, allowing for inspection of Event Hub metadata and providing a guided experience towards specific Event Hub operations such as the creation of producers and consumers.
+
+- An **Event Hub producer** is a source of telemetry data, diagnostics information, usage logs, or other log data, as part of an embedded device solution, a mobile device application, a game title running on a console or other device, some client or server based business solution, or a web site.
 
-- **Event publishers**: Any entity that sends data to an event hub is an event producer, or event publisher. Event publishers can publish events using HTTPS or AMQP 1.0 or Kafka 1.0 and later. Event publishers use a Shared Access Signature (SAS) token to identify themselves to an event hub, and can have a unique identity, or use a common SAS token.
+- An **Event Hub consumer** picks up such information from the Event Hub and processes it. Processing may involve aggregation, complex computation, and filtering. Processing may also involve distribution or storage of the information in a raw or transformed fashion. Event Hub consumers are often robust and high-scale platform infrastructure parts with built-in analytics capabilities, like Azure Stream Analytics, Apache Spark, or Apache Storm.
 
-- **Event consumers**: Any entity that reads event data from an event hub is an event consumer. All Event Hubs consumers connect via the AMQP 1.0 session and events are delivered through the session as they become available. The client does not need to poll for data availability.
+- A **partition** is an ordered sequence of events that is held in an Event Hub. Azure Event Hubs provides message streaming through a partitioned consumer pattern in which each consumer only reads a specific subset, or partition, of the message stream. As newer events arrive, they are added to the end of this sequence. The number of partitions is specified at the time an Event Hub is created and cannot be changed.
 
-- **SAS tokens**: Event Hubs uses Shared Access Signatures, which are available at the namespace and event hub level. A SAS token is generated from a SAS key and is an SHA hash of a URL, encoded in a specific format. Using the name of the key (policy) and the token, Event Hubs can regenerate the hash and thus authenticate the sender.
+- A **consumer group** is a view of an entire Event Hub. Consumer groups enable multiple consuming applications to each have a separate view of the event stream, and to read the stream independently at their own pace and from their own position. There can be at most 5 concurrent readers on a partition per consumer group; however it is recommended that there is only one active consumer for a given partition and consumer group pairing. Each active reader receives all of the events from its partition; if there are multiple readers on the same partition, then they will receive duplicate events.
 
-For more information about these concepts, see [Features and terminology in Azure Event Hubs](https://docs.microsoft.com/en-ca/azure/event-hubs/event-hubs-features).
+For more concepts and deeper discussion, see: [Event Hubs Features](https://docs.microsoft.com/en-us/azure/event-hubs/event-hubs-features). Also, the concepts for AMQP are well documented in [OASIS Advanced Messaging Queuing Protocol (AMQP) Version 1.0](http://docs.oasis-open.org/amqp/core/v1.0/os/amqp-core-overview-v1.0-os.html).
 
 # Examples