We assume that you already know what components are. See Chapter 26, Components for an overview.
Only some of the components in a graph are initial nodes. These are called Readers.
Readers can read data from input files (both local and remote), receive it from the connected optional input port, or read it from a dictionary. One component only generates data. Since it is also an initial node, we will describe it here.
Components can have different properties. But they also can have some in common. Some properties are common for all of them, others are common for most of the components, or they are common for Readers only. You should learn:
We can distinguish Readers according to what they can read:
One component only generates data:
DataGenerator generates data.
Other Readers read data from files.
Flat files:
CSVReader reads data from flat files (delimited or fixed length).
ParallelReader reads data from delimited flat files using more threads.
ComplexDataReader reads data from really ugly flat files whose structure is heterogeneous or mutually dependent and it uses a neat GUI to achieve that.
MultiLevelReader reads data from flat files with a heterogeneous structure.
Other files:
CloudConnectDataReader reads data from files in CloudConnect binary format.
XLSDataReader reads data from XLS or XLSX files.
DBFDataReader reads data from dBase files.
XMLExtract reads data from XML files using SAX technology.
XMLXPathReader reads data from XML files using XPath queries.
Other Readers read data from various SaaS applications.
Applications:
SF Reader reads data from the Salesforce.
Google Analytics Reader reads data from the Google Analytics.
HTTPConnector sends HTTP requests and receives responses from web server.
WebServiceClient calls a web-service and maps response to output ports.
EventStore Reader reads data from the EventStore.
Other Readers unload data from databases.
Databases:
DBInputTable unloads data from database using JDBC driver.
Other Readers receive JMS messages or read directory structure.
JMS messages:
JMSReader converts JMS messages into data records.
Directory structure:
LDAPReader converts directory structure into data records.
Email messages:
EmailReader Reads email messages.