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# Chapter 48. Readers

Readers can read data from input files (both local and remote), receive it from the connected optional input port, read it from a dictionary, from a database, or from a JMS.

One component only generates data. Since it is also an initial node, we will describe it here.

We can distinguish Readers according to what they can read:

##### Generating data

A DataGenerator component generates data.

##### Reading flat files

- FlatFileReader reads data from flat files (delimited or fixed length).

- ParallelReader reads data from delimited flat files using more threads.

- ComplexDataReader reads data from 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.

##### Reading XML files

- XMLExtract reads data from XML files using SAX technology.

- XMLReader reads data from XML files using DOM technology.

- XMLXPathReader reads data from XML files using XPath queries.

Generally, use XMLExtract. If you require more complex XPath queries, use XMLReader.

##### Reading JSON files

- JSONExtract reads data from JSON files using XPath queries. Based on SAX.

- JSONReader reads data from JSON files using XPath queries. Based on DOM.

##### Reading other files

- CloverDataReader reads data from files in Clover binary format.

- SpreadsheetDataReader reads data from XLS or XLSX files.

- DBFDataReader reads data from dBase files.

- HadoopReader reads data from Hadoop sequence files.

##### Reading databases

- DBInputTable unloads data from database using JDBC driver.

- QuickBaseRecordWriter reads data from the QuickBase online database.

- QuickBaseImportCSV reads data from the QuickBase online database using queries.

- LotusReader reads data from Lotus Notes or Lotus Domino database.

- MongoDBReader reads data from the MongoDB NoSQL database.

- SalesforceBulkReader reads data from the Salesforce cloud platform using Bulk API.

- SalesforceReader reads data from the Salesforce cloud platform using SOAP API.

##### Reading JMS messages, directory structure or emails.

- JMS messages:

  - JMSReader converts JMS messages into data records.

- Directory structure:

  - LDAPReader converts directory structure into data records.

- Email messages:

  - EmailReader Reads email messages.

##### See also

Common Properties of Components
Specific Attribute Types
Common Properties of Readers

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