Home > Product Manuals > Model Annotations > Model annotations

Model annotations

A model can carry annotations as specially-formatted comments. The general format for such annotations is as follows:

# <tag>: <value>

The annotation must be a comment in the target language and it must occupy the whole line. If the annotation tag is recognized, the value becomes associated with the tag. A tag contains a series of tag elements separated by dots. The first tag element is either ‘fastscore’ or ‘ModelOp’.

Certain annotations are slot-specific. They are relevant for a particular stream slot or a group of slots. The slot scope is always the last element of the tag of a slot-specific annotation. The following slot scopes are supported:

Slot scope Applicable to Example
<slot-number> The slot # fastscore.schema.3: schema-1
<slot-name> The named slot #fastscore.schema.err: schema-1
$all All stream slots #fastscore.schema.$all: schema-1
$in All input slots (0, 2, 4,…) #fastscore.recordsets.$in: yes
$out All output slots (1, 3, 5,…) #fastscore.recordsets.$out: false

The slot scope can be omitted. If omitted, the default slot scope is assumed. The default scope depends on the annotation tag.

The current list of supported model annotations is given in the table below.

Tag Slot-specific Description Allowed values Example
fastscore.schema.<slot> Yes (default scope: $all) The name of the Avro schema   # fastscore.schema.0: schema-1
fastscore.recordsets.<slot> Yes (default scope: $all) The ‘recordsets’ flag true / false / yes / no # fastscore.recordsets.$in: yes
fastscore.action.<slot> Yes (default score: $in) The name of the action function (defaults to ‘action’) / none # fastscore.action: score_report
fastscore.slot.<slot> Yes (default score: $all) Set to ‘unused’ to disable the slot. in-use / unused #fastscore.slot.1: unused
fastscore.module-attached No The name of the code module included as a model attachment   #fastscore.module-attached: mylib
fastscore.snapshots No Set to ‘eof’ to automatically take a model snapshot when the run completes. none / eof #fastscore.snapshots: eof

A fastscore.slot.<num-or-name>: in-use annotation marks the slot as being used by the model. If a slot number or name is mentioned in the schema/recordsets/action annotation it implicitly marks the slot as being in use. Note that in-use annotation can not refer to $all/$in/$out scopes. On the other hand, the fastscore.slot.<slot-scope>: unused annotation cancels the effect of any previous annotations that mentioned the <slot-scope>. For example, fastscore.slot.$output: unused indicate that the model does not produce any outputs. The ‘unused’ annotation can remove the default slots (0 and 1) from consideration.

Setting fastscore.action to none disables the action callbacks. The model becomes purely explicit. Explicit models read from stream slots directly and may exit before all streams reach EOF.

The annotations in the table below are deprecated and should not be used for new models. However, they are recognized by the Engine.

Deprecated annotation Equivalent annotation(s)
fastscore.input: <schema> fastscore.schema.0: <schema>
fastscore.output: <schema> fastscore.schema.1: <schema>
fastscore.recordsets: none/input/output/both fastscore.recordsets.0: <yes/no> /fastscore.recordsets.1: <yes/no>

PFA models

PFA models currently do not support multiple input/output stream slots. Thus their annotations do not use a slot scope. Annotations of a PFA model are represented as subelements of a ‘metadata’ element. The supported annotations are given in the table below.

Annotation Description Default
“recordsets”: “none” / “recordsets”: “input” / “recordsets”: “output” / “recordsets”: “both” The ‘recordsets’ flag “none”
“snapshots”: “none” / “snapshots”: “eof” Set to ‘eof’ to automatically take a model snapshot when the run completes. “none”

Note that for a PFA model keeps its schemas in two (mandatory) top-level elements: ‘input’ and ‘output’. An example of an annotated PFA model:

  "input": "int",
  "output": "int",
  "metadata": {
    "recordsets": "none",
    "snapshots": "eof"
  "action": ...