16. Introduction

In Spring Cloud Data Flow, a basic stream defines the ingestion of event data from a source to a sink that passes through any number of processors. Streams are composed of Spring Cloud Stream applications and the deployment of stream definitions is done via the Data Flow Server (REST API). The Getting Started section shows you how to start the server and how to start and use the Spring Cloud Data Flow shell.

A high level DSL is used to create stream definitions. The DSL to define a stream that has an http source and a file sink (with no processors) is shown below

http | file

The DSL mimics UNIX pipes and filters syntax. Default values for ports and filenames are used in this example but can be overridden using -- options, such as

http --server.port=8091 | file --directory=/tmp/httpdata/

To create these stream definitions you use the shell or make an HTTP POST request to the Spring Cloud Data Flow Server. For more information on making HTTP request directly to the server, consult the REST API Guide.