WarmTransfer
webex contact center · published

Pebble template syntax and filters in Flow Designer

Verified 2026-09-15 · 10 sources · tier 2

Also known as Pebble, Pebble Templates, epoch filter.

Flow Designer input fields use the open-source Pebble Templates expression syntax, and the source article names no version of it 4. The documentation names 10 operator symbols, 2 filters, and 1 function of the expression language, delegating the rest to an external wiki 1.

Syntax and usage rules

Cisco instructs that single quotes be used instead of double quotes inside an expression and gives no reason for this rule 8. An expression written without its double curly braces throws a flow error, though the documentation states this for the Condition activity only 5. A text-to-speech message of more than 1 line requires a Pebble escape filter for the system to play it 6.

For date and time values, Cisco instructs that the now function not be used to obtain the current time in milliseconds because it uses a simple date format, directing the author to the epoch filter instead 7. In certain activity configurations, 2 unrelated expression syntaxes coexist: the Pebble double-brace form for flow variables and a JSON path form for parsing a response body 9. In the field, Cisco advises against complex expressions when configuring multiple variables in 1 Set Variable activity, but defines neither complex nor the consequence 2.

Validation and error behavior

Flow validation checks expressions for structural errors only and cannot evaluate a function or check that a variable resolves to the expected value 10. An invalid expression surfaces either as design-time error code FC1009 or as a system error during execution of the Set Variable activity, and the documentation never relates the 2 failure surfaces 3.

See also

See also Webex Contact Center Flow Designer architecture. See also The Webex Contact Center Flow Designer activity set. See also The Flow Designer failure code vocabularies.

Applicability

Applies to: Cisco Webex Contact Center. Sources checked 2026-09-15.

What remains uncertain

Which logic operators the expression language supports is not covered by the sources below. What makes an expression invalid at design time is not covered by the sources below. Whether the missing-brace error applies outside the Condition activity is not covered by the sources below. Which Pebble release the platform runs is not covered by the sources below.

See also

Part of

Related to

Referenced by

Sources

  1. 1
    The article names 10 operator symbols 2 filters and 1 function of the expression language and delegates the rest to an external wiki.
    Build and manage flows with Flow Designer · Flow Designer, Pebble template syntax and the epoch filter section · Checked 2026-09-15
  2. 2
    Cisco advises against complex expressions when configuring multiple variables in one Set Variable activity and defines neither complex nor the consequence.field report
    Build and manage flows with Flow Designer · Flow Designer, Set Variable activity · Checked 2026-09-15
  3. 3
    An invalid expression surfaces either as design-time error code FC1009 or as a system error during execution of the Set Variable activity and the article never relates the two.
    Build and manage flows with Flow Designer · Flow Designer, Understand error codes and the global error handler · Checked 2026-09-15
  4. 4
    Flow Designer input fields use the open-source Pebble Templates expression syntax and the article names no version of it.
    Build and manage flows with Flow Designer · Flow Designer, Pebble template syntax · Checked 2026-09-15
  5. 5
    An expression written without its double curly braces throws a flow error and the article states this for the Condition activity only.
    Build and manage flows with Flow Designer · Flow Designer, Condition activity · Checked 2026-09-15
  6. 6
    A text-to-speech message of more than one line requires a Pebble escape filter for the system to play it.
    Build and manage flows with Flow Designer · Flow Designer, text-to-speech message guidance · Checked 2026-09-15
  7. 7
    Cisco instructs that the now function not be used to obtain the current time in milliseconds because it uses a simple date format and directs the author to the epoch filter instead.
    Build and manage flows with Flow Designer · Flow Designer, date time variables and the epoch filter · Checked 2026-09-15
  8. 8
    Cisco instructs that single quotes be used instead of double quotes inside an expression and gives no reason.
    Build and manage flows with Flow Designer · Flow Designer, text-to-speech and expression guidance · Checked 2026-09-15
  9. 9
    Two unrelated expression syntaxes are used in the same activity configuration: the Pebble double brace form for flow variables and a JSON path form for parsing a response body.
    Build and manage flows with Flow Designer · Flow Designer, Parse activity and HTTP Request content type · Checked 2026-09-15
  10. 10
    Flow validation checks expressions for structural errors only and cannot evaluate a function or check that a variable resolves to the expected value.
    Build and manage flows with Flow Designer · Flow Designer, validate a flow · Checked 2026-09-15

Documents

tier 2 current vendor documentation

Build and manage flows with Flow Designer

Cisco Systems, Inc. (Webex Help Center) · 2026-09-03 · accessed 2026-09-05

Cite this page

APA

WarmTransfer. (2026, September 15). Pebble template syntax and filters in Flow Designer. WarmTransfer. https://warmtransfer.net/knowledge/pebble-template-expressions

BibTeX

@misc{warmtransfer-pebble-template-expressions,
  title  = {Pebble template syntax and filters in Flow Designer},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/pebble-template-expressions},
  note   = {Verified 2026-09-15}
}