Source - ClockSourceBuilder

Source.ClockSourceBuilder

A helper class to build a data

Source, which populates a data Stream with data. Data sources can range from simple clocks to complex database queries or API requests.

A corresponding

Template can be created using .toTemplate().

Remarks

See

Ingest Structured Data for a related learning module.

Type parameters

Name	Type
T	extends EastType
Inputs	extends Record

Hierarchy

• AbstractSourceBuilder

  ↳ ClockSourceBuilder

Source

error

▸ error(config):

ClockSourceBuilder

Check the source outputs for validity and identify any errors. When the if predicate returns true the source will be terminated with an error message and output data will not be produced.

Parameters

Name	Type	Description
config	Object	the error message and predicate
config.if	(value: Variable, inputs: Inputs) => EastFunction	If true an error will be created
config.message	string | (value: Variable, inputs: Inputs) => EastFunction	The message in the case that an error is created

Returns

ClockSourceBuilder

a new

SourceBuilder

Example

 const source = new SourceBuilder("FloatSource")
     .input({ name: "max", stream: max_stream })
     .writeable(FloatType)
     .error({
         if: (value, { max }) => Greater(value, max),
         message: (value) => StringJoin`The value ${value} exceeds maximum`
     })

Inherited from

AbstractSourceBuilder.error

---

input

▸ input(config):

ClockSourceBuilder<T, Inputs & { [K in string]: Variable }>

Add a stream as input to the SourceBuilder, which can be used in expressions to configure how the

Source will access the data (such as a URL or password), the output data, or any data assertions (preconditions and postconditions).

Type parameters

Name	Type
Name	extends string
S	extends EastType

Parameters

Name	Type	Description
config	Object	the configuration for the input
config.name	Name extends "input" | keyof Inputs ? never : Name	the name to give the input Variable
config.stream	Stream	the input stream (the stream and associated preconditions)

Returns

ClockSourceBuilder<T, Inputs & { [K in string]: Variable }>

a new

SourceBuilder

Example

 const other = Stream("Other", FloatType)
 const source = new SourceBuilder("Source")
     .input({ name: "other", stream: other })
     .clock({ cron: "0 * * * *" })
     .toSource()

---

log

▸ log(config):

ClockSourceBuilder

Produce log messages based on the source outputs and inputs. When the if predicate returns true source will register a warning with a message, but will proceed to proceed to produce output data.

Parameters

Name	Type	Description
config	Object	the log message and optional predicate
config.if?	(value: Variable, inputs: Inputs) => EastFunction	If true a log message will be produced (optional)
config.message	string | (value: Variable, inputs: Inputs) => EastFunction	The message in the case that a warning is created

Returns

ClockSourceBuilder

a new

SourceBuilder

Example

 const source = new SourceBuilder("FloatSource")
     .input({ name: "max", stream: max_stream })
     .writeable(FloatType)
     .log({
         if: (value, { max }) => Greater(value, max),
         message: (value) => StringJoin`The value ${value} exceeds maximum`
     })

Inherited from

AbstractSourceBuilder.log

---

outputStream

▸ outputStream():

Stream

Return the

Stream containing the output of the datasource.

Returns

Stream

Example

// Create a datastream which is updated to the current time at the beginning of every hour
const hourly = new SourceBuilder("Hourly")
    .clock({ cron: "0 * * * *" })
    .outputStream()

Overrides

AbstractSourceBuilder.outputStream

---

toTemplate

▸ toTemplate():

Template

Return a

Template fragment containing the Streams and TaskDescriptions built by this builder.

Returns

Template

Example

// Create a datastream which is updated to the current time at the beginning of every hour
export default new SourceBuilder("Hourly")
    .clock({ cron: "0 * * * *" })
    .toTemplate()

Overrides

AbstractSourceBuilder.toTemplate

---

warn

▸ warn(config):

ClockSourceBuilder

Check the source outputs for validity and produce warnings as necessary. When the if predicate returns true the source will register a warning with a message, but will proceed to proceed to produce output data.

Parameters

Name	Type	Description
config	Object	the warning message and predicate
config.if	(value: Variable, inputs: Inputs) => EastFunction	If true a warning will be produced
config.message	string | (value: Variable, inputs: Inputs) => EastFunction	The message in the case that a warning is created

Returns

ClockSourceBuilder

a new

SourceBuilder

Example

 const source = new SourceBuilder("FloatSource")
     .input({ name: "max", stream: max_stream })
     .writeable(FloatType)
     .warn({
         if: (value, { max }) => Greater(value, max),
         message: (value) => StringJoin`The value ${value} exceeds maximum`
     })

Inherited from

AbstractSourceBuilder.warn