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For a variety of components, there is the need to transform messages and compose those transformations in a pluggable way. For this purpose, there is a simple DSL to allow functions to be defined for common transformations and to have those functions be composed.

Transformation Language

 

The functions currently supported are:

  • TO_LOWER(string) : Transforms the first argument to a lowercase string
  • TO_UPPER(string) : Transforms the first argument to an uppercase string
  • TO_STRING(string) : Transforms the first argument to a string
  • TO_INTEGER(x) : Transforms the first argument to an integer
  • TO_DOUBLE(x) : Transforms the first argument to a double
  • TRIM(string) : Trims whitespace from both sides of a string.
  • JOIN(list, delim) : Joins the components of the list with the specified delimiter
  • SPLIT(string, delim) : Splits the string by the delimiter. Returns a list.
  • GET_FIRST(list) : Returns the first element of the list
  • GET_LAST(list) : Returns the last element of the list
  • GET(list, i) : Returns the i'th element of the list (i is 0-based).
  • MAP_GET(key, map, default) : Returns the value associated with the key in the map. If the key does not exist, the default will be returned. If the default is unspecified, then null will be returned.
  • DOMAIN_TO_TLD(domain) : Returns the TLD of the domain.
  • DOMAIN_REMOVE_TLD(domain) : Remove the TLD of the domain.
  • REMOVE_TLD(domain) : Removes the TLD from the domain.
  • URL_TO_HOST(url) : Returns the host from a URL
  • URL_TO_PROTOCOL(url) : Returns the protocol from a URL
  • URL_TO_PORT(url) : Returns the port from a URL
  • URL_TO_PATH(url) : Returns the path from a URL
  • TO_EPOCH_TIMESTAMP(dateTime, format, timezone) : Returns the epoch timestamp of the dateTime given the format. If the format does not have a timestamp and you wish to assume a given timestamp, you may specify the timezoneoptionally.

Example Transformation:

TO_EPOCH_TIMESTAMP(timestamp, 'yyyy-MM-dd HH:mm:ss', MAP_GET(dc, dc2tz, 'UTC'))

For a message with a timestamp and dc field, we want to set the transform the timestamp to an epoch timestamp given a timezone which we will lookup in a separate map, called dc2tz.

This will convert the timestamp field to an epoch timestamp based on the

  • Format yyyy-MM-dd HH:mm:ss
  • The value in dc2tz associated with the value associated with field dc, defaulting to UTC
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