17.2. Parsing and Validation

GeoMesa provides options for dealing with bad input records which can be configured on your converter. For example, you may want to skip over bad records for some input sources or fail entire files in other cases. The Converter framework provides a few options that can help control how errors in input data are handled.

17.2.1. Validators

At their core, converters transform input streams into SimpleFeatures. Validators provide hooks to validate properties of those SimpleFeatures before they are written to GeoMesa. For example, you may want to validate that there is a geometry field and that the geometry is valid.

There are currently three validators available for use with GeoMesa converters:

• has-geo - Ensure that the SimpleFeature has a geometry and it is non-null
• has-dtg - Ensure that the SimpleFeature has a date and it is non-null
• z-index - Ensure the Geometry and Date are within the space/time bounds of GeoMesa Z-Index implementations (i.e. Z2, Z3, XZ2, XZ3)

By default the has-geo and has-dtg validators are enabled. To enable other validators add this to the options block of your typesafe converter config:

geomesa.converters.myconverter {
  options {
    validators = ["has-dtg", "has-geo", "z-index"]
  }
}

Validation can be disabled by setting it to an empty array.

17.2.2. Error Mode

There are two types of modes for handling errors:

• skip-bad-records
• raise-errors

raise-errors mode will throw an IOException if bad data is detected based on parsing or validation. This can be especially useful when first developing and testing a converter definition. skip-bad-records mode will still provide debug level logging but will not throw an exception. To configure the error mode add the following option to your converter’s typesafe config:

geomesa.converters.myconverter {
  options {
    error-mode = "raise-errors"
  }
}

17.2.3. Parse Mode

The parse mode option allows you to control whether a file is parsed incrementally or fully before being converted. This is important when it comes to validation. There are two modes available:

• incremental
• batch

Since converters provide iterators of SimpleFeatures, the default parse mode is incremental which provides better performance and less memory overhead. Using incremental parse mode means that data may be partially ingested into GeoMesa before an error is raised. In most cases this is appropriate and can be handled by the client code.

Using batch mode will buffer an entire input stream or file in memory to validate the data which is less performant and requires more memory. batch mode does, however, prevent partially ingested data streams. It is unlikely that you need to use batch mode in environments where data is properly sanitized.

To configure the parse mode use add an option to your converter’s typesafe config:

geomesa.converters.myconverter {
  options {
    parse-mode = "incremental"
  }
}

17.2.4. Logging

To view validation logs you can enable debug level logging on the package org.locationtech.geomesa.convert.

By default, logging will just show the field that failed. To show the entire record, along with the stack trace, you can set options.verbose = true.

17.2.5. Transactional Considerations

Most of the datastores that GeoMesa works with (Accumulo, HBase, etc) do not provide transactions. Therefore, streaming data in and out of a converter and into an ingest pipeline is not transactional. To mimic transactions you can use a batch parse mode with raise-errors error mode and likely with the z-index validator. Note that this may increase your memory requirements and hurt performance:

geomesa.converters.myconverter {
  options {
    validators = [ "z-index" ]
    parse-mode = "batch"
    error-mode = "raise-errors"
  }
}

If you need notification of bad input data you may consider using an error mode of raise-errors with an incremental parse mode:

geomesa.converters.myconverter {
  options {
    validators = [ "z-index" ]
    parse-mode = "incremental"
    error-mode = "raise-errors"
  }
}

If you are using a framework such as the GeoMesa Nifi processor, then the file will still be routed to an error relationship but you may experience partially ingested data. See GeoMesa NiFi Bundle for more info.