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## Common Properties of Readers

- Readers allow you to specify the location of input data.

  See examples of the File URL attribute for reading from local and remote files, through proxy, input port and dictionary in Supported File URL Formats for Readers.

- Readers allow you to view the source data. See Viewing Data on Readers.

- Readers can read data from the input port. E.g. you can read URLs of the files to be read. See Input Port Reading.

- Readers can read only the new records. See Incremental Reading.

- Readers can skip specific number of initial records or set limit on number of records to be read. See Selecting Input Records.

- Readers allows you to configure a policy related to parsing incomplete or invalid data record. See Data Policy.

- Some readers can log information about errors.

- XML-reading components allows you to configure the parser. See XML Features.

- In some Readers, a transformation can be or must be defined. For information about transformation templates for transformations written in CTL see:

  CTL Templates for Readers

- Similarly, for information about transformation interfaces that must be implemented in transformations written in Java see:

  Java Interfaces for Readers

### Overview of Readers

Table 48.1. Readers Comparison

Component | Data source | Input ports | Output ports | Each to all outputs [1] | Different to different outputs [2] | Transformation | Transf. req. | Java | CTL | Auto-propagated metadata
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
CloverDataReader | clover binary file | 0 | 1-n |  |  |  |  |  |  |
ComplexDataReader | flat file | 1 | 1-n |  |  |  |  |  |  |
DataGenerator | none | 0 | 1-n |  |  |  |  |  |  |
DBFDataReader | dBase file | 0-1 | 1-n |  |  |  |  |  |  |
DBInputTable | database | 0 | 1-n |  |  |  |  |  |  |
EmailReader | email messages | 0 | 1 | - | - |  |  |  |  |
FlatFileReader | flat file | 0-1 | 1-2 |  |  |  |  |  |  |
HadoopReader | Hadoop sequence file | 0 | 1 |  |  |  |  |  |  |
JavaBeanReader | dictionary | 0 | 1-n |  |  |  |  |  |  |
JMSReader | jms messages | 0 | 1 | - | - |  |  |  |  |
JSONExtract | JSON file | 0-1 | 1-n |  |  |  |  |  |  |
JSONReader | JSON file | 0-1 | 1-n |  |  |  |  |  |  |
LDAPReader | LDAP directory tree | 0 | 1-n |  |  |  |  |  |  |
LotusReader | Lotus Notes | 0 | 1 |  |  |  |  |  |  |
MongoDBReader | database | 0-1 | 1-2 |  |  |  |  |  |  |
MultiLevelReader | flat file | 1 | 1-n |  |  |  |  |  |  |
ParallelReader | flat file | 0 | 1 |  |  |  |  |  |  |
QuickBaseRecordReader | QuickBase | 0-1 | 1-2 |  |  |  |  |  |  |
QuickBaseQueryReader | QuickBase | 0 | 1 |  |  |  |  |  |  |
SalesforceBulkReader | Salesforce | 0 | 1 |  |  |  |  |  |  |
SalesforceReader | Salesforce | 0 | 1 |  |  |  |  |  |  |
SpreadsheetDataReader | XLS(X) file | 0-1 | 1-2 |  |  |  |  |  |  |
UniversalDataReader | flat file | 0-1 | 1-2 |  |  |  |  |  |  |
XMLExtract | XML file | 0-1 | 1-n |  |  |  |  |  |  |
XMLReader | XML file | 0-1 | 1-n |  |  |  |  |  |  |
XMLXPathReader | XML file | 0-1 | 1-n |  |  |  |  |  |  |
[1] Component sends each data record to all of the connected output ports. [2] Component sends different data records to different output ports using return values of the transformation (DataGenerator and MultiLevelReader). See Return Values of Transformations for more information. XMLExtract, XMLReader and XMLXPathReader send data to ports as defined in their Mapping or Mapping URL attribute.

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