Explore common elements of stream processing architecture
There are many technologies that you can use to implement a stream processing solution, but while specific implementation details may vary, there are common elements to most streaming architectures.
A general architecture for stream processing
At its simplest, a high-level architecture for stream processing looks like this:
- An event generates some data. This might be a signal being emitted by a sensor, a social media message being posted, a log file entry being written, or any other occurrence that results in some digital data.
- The generated data is captured in a streaming source for processing. In simple cases, the source may be a folder in a cloud data store or a table in a database. In more robust streaming solutions, the source may be a "queue" that encapsulates logic to ensure that event data is processed in order and that each event is processed only once.
- The event data is processed, often by a perpetual query that operates on the event data to select data for specific types of events, project data values, or aggregate data values over temporal (time-based) periods (or windows) - for example, by counting the number of sensor emissions per minute.
- The results of the stream processing operation are written to an output (or sink), which may be a file, a database table, a real-time visual dashboard, or another queue for further processing by a subsequent downstream query.
Real-time analytics in Azure
Microsoft Azure supports multiple technologies that you can use to implement real-time analytics of streaming data, including:
- Azure Stream Analytics: A platform-as-a-service (PaaS) solution that you can use to define streaming jobs that ingest data from a streaming source, apply a perpetual query, and write the results to an output.
- Spark Structured Streaming: An open-source library that enables you to develop complex streaming solutions on Apache Spark based services, including Azure Synapse Analytics, Azure Databricks, and Azure HDInsight.
- Azure Data Explorer: A high-performance database and analytics service that is optimized for ingesting and querying batch or streaming data with a time-series element, and which can be used as a standalone Azure service or as an Azure Synapse Data Explorer runtime in an Azure Synapse Analytics workspace.
Sources for stream processing
The following services are commonly used to ingest data for stream processing on Azure:
- Azure Event Hubs: A data ingestion service that you can use to manage queues of event data, ensuring that each event is processed in order, exactly once.
- Azure IoT Hub: A data ingestion service that is similar to Azure Event Hubs, but which is optimized for managing event data from Internet-of-things (IoT) devices.
- Azure Data Lake Store Gen 2: A highly scalable storage service that is often used in batch processing scenarios, but which can also be used as a source of streaming data.
- Apache Kafka: An open-source data ingestion solution that is commonly used together with Apache Spark. You can use Azure HDInsight to create a Kafka cluster.
Sinks for stream processing
The output from stream processing is often sent to the following services:
- Azure Event Hubs: Used to queue the processed data for further downstream processing.
- Azure Data Lake Store Gen 2 or Azure blob storage: Used to persist the processed results as a file.
- Azure SQL Database or Azure Synapse Analytics, or Azure Databricks: Used to persist the processed results in a database table for querying and analysis.
- Microsoft Power BI: Used to generate real time data visualizations in reports and dashboards.
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