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Message

Events traversing layline.io Workflows are instantiated as a Message. This class exposes a number of properties and methods to extract and set data within messages.

To understand the anatomy of a message please read the respective chapter in the documentation.

Example Message Structure​

Assume we have the following data dictionary structure

  • Header
    • IOT
      • RECORD_TYPE
      • DEVICE_NO
  • Detail
    • IOT
      • RECORD_TYPE
      • TIME
      • MEASUREMENT
  • Trailer
    • IOT
      • RECORD_TYPE
      • COUNT

Then in a Javascript processor we can do this:

...
export function onMessage() {
    if (message.typeName === 'Header') {
        onHeader (message);
    } else if (message.typeName === 'Detail') {
        onDetail(message);
    } else if (message.typeName === 'Trailer') {
        onDetail(message);
    }

    // send the message on through OUTPUT_PORT of Processor
    stream.emit(message, OUTPUT_PORT);
}
...

And this:

...
// Handle a detail record type
function onDetail (message) {
    const m = message.data.IOT.MEASUREMENT;

    const VENDOR = Status.getVendorByName('MyVendorLongName');

    if (m < 0) {
         message.addStatus(Severity.ERROR, Status.create(VENDOR, 'ILLEGAL_MEASUREMENT', m));
    }
}
...

Properties​

data​

data: Object

The data of the message. It is a nested object structure that reflects the structure of the data dictionary of this message.

Example​

// Create Detail
const detailMessage = dataDictionary.createMessage(dataDictionary.type.Detail);
detailMessage.data.PRODUCT = {
    RECORD_TYPE       : "D",
    ID                : message.data.Id,
    CODE              : message.data.Code,
    NAME              : message.data.Name,
    CATEGORY          : message.data.Category,
    PRICE             : message.data.Price,
    STOCK_QUANTITY    : message.data.StockQuantity,
    COLOR             : message.data.Color,
    LAUNCH_DATE       : message.data.LaunchDate,
}
// stream.logInfo(f"detailMessage: {detailMessage.toJson()})")
stream.emit(detailMessage, OUTPUT_PORT);

id​

id: string

The unique identifier of the message. This is a consecutive number starting with "1" for the first message. It is used to uniquely identify a message within a stream. Cloning a message will generate a new id, whereas the original message will keep its id and the cloned message will have the original message number appended by a "." and a new consecutive number. For example, "1.1", "1.2", "1.3", ... for each clone of the original message.

Example​

// Accessing the id of a message
const id = message.id;

typeName​

typeName: string

The type name of the message. This is the name of the data dictionary type that the message represents.

Example​

const typeName = message.typeName;
// e.g, If in your data dictionary you have a type called "MyType", then this will return "MyType"
if (message.typeName === 'MyType') {
    // do something
}

Methods​

addStatus()​

addStatus(severity, status, addToLog?): void

Adds a Status to a message. The Status must have been created with Status.create or otherwise instantiated.

Parameters​

severity​

Severity

Severity value.

status​

Status

The Status which should be added.

addToLog?​

boolean = true

Signals whether the Status shall also be added to the log, or not. Will be added by default if not specified. If true then the Status will be visible in the Stream Log of the Audit Trail.

Returns​

void

Example​

 if (error) {
     message.addStatus(Severity.ERROR, Status.create(VENDOR, 'ILLEGAL_VALUE', valueString));
 }

clone()​

clone(): Message

Creates a full clone of a Message

clonedMessage = message.clone();

Returns​

Message

A copy of a Message

commit()​

commit(): Message

Commits the message, typically used with message queues or streaming platforms.

This method is used to acknowledge the successful processing of a message. The exact behavior depends on the underlying system:

  • For an SQS queue, it deletes the message from the queue.
  • For a Kafka topic, it commits the offset of the consumer.

Calling this method indicates that the message has been successfully processed and should not be redelivered.

Returns​

Message

Returns the message instance for method chaining.

Example​

export function onMessage() {
  try {
    // Process the message
    const result = processMessage(message);

    if (result.success) {
      // If processing was successful, commit the message
      message.commit();
      print("Message processed and committed successfully");
    } else {
      print("Message processing failed, not committing");
    }
  } catch (error) {
    print("Error processing message:", error);
    // In case of an error, you might choose not to commit
    // so that the message can be reprocessed
  }
}

function processMessage(msg) {
  // Implement your message processing logic here
  // Return an object indicating success or failure
}

exists()​

exists(type): boolean

Checks if a known data structure is recognized within a given Message. Data structures are spawned into existence by the definition of data formats (Format Assets). You can test a particular Message on whether a specific structure is present within a message by using this method.

This is typically used to check whether a message is of a certain type, or not.

Parameters​

type​

DataDictionaryEntity

Path to data dictionary structure which you want to test for existence in the message (DataDictionaryEntity.)

Returns​

boolean

True, if it exists, else false.

Example​

// Get the access path to a structure within the compiled data dictionary
const MY_RECORD_TYPE = dataDictionary.type.MyFormat.Detail;

// Test message against the existence of the data dictionary structure.
if (message.exists(MY_RECORD_TYPE)) {
    ...
}

findStatus()​

findStatus(value): Status[]

Finds and returns an array of status entries attached to the message based on the provided filter.

This method allows you to search for status entries using three different approaches:

  1. By Vendor: Find all statuses from a specific vendor.
  2. By Severity: Find all statuses of a specific severity level.
  3. By Custom Function: Use a custom filter function to find statuses based on any criteria.

Parameters​

value​

Vendor | Severity | ((status) => boolean)

The filter to apply:

  • If a Vendor is provided, it returns all statuses from that vendor.
  • If a Severity is provided, it returns all statuses of that severity level.
  • If a function is provided, it should take a Status as input and return a boolean. The method will return all statuses for which this function returns true.

Returns​

Status[]

An array of Status objects that match the provided filter. Returns an empty array if no matching statuses are found.

Examples​

// Finding statuses by Vendor
const VENDOR = Status.getVendorByName('MyVendorName');
const vendorStatuses = message.findStatus(VENDOR);
vendorStatuses.forEach(status => {
    print(`Found status: ${status.code} - ${status.message}`);
});
// Finding statuses by Severity
const errorStatuses = message.findStatus(Severity.ERROR);
if (errorStatuses.length > 0) {
    print(`Message has ${errorStatuses.length} error statuses`);
}
// Finding statuses using a custom filter function
function hasSpecificCode(status) {
    return status.code === "SPECIFIC_CODE";
}
const specificStatuses = message.findStatus(hasSpecificCode);
specificStatuses.forEach(status => {
    print(`Found status with specific code: ${status.message}`);
});
// Using an arrow function for filtering
const highPriorityStatuses = message.findStatus(s => [Severity.WARNING, Severity.ERROR].includes(s.severity));
highPriorityStatuses.forEach(status => {
    print(`High priority status: ${status.severity} - ${status.message}`);
});

getBigInteger()​

getBigInteger(entity): Uint8Array

Return a BigInteger typed value from a message field. Important!: Please note that this method returns a Java object "Big Integer" (a Java native data type). Because of this you cannot reliably use simple Javascript number operators without risking implicit conversion errors.

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

Returns​

Uint8Array

Number in Java native BigInteger type.

Example​

const n = message.getBigInteger(dataDictionary.type.Detail.CSV.A_REALLY_BIG_NUMBER_FIELD);

// Compare BigInteger to another BigInteger
const BigInteger = Java.type("java.math.BigInteger");
x = new BigInteger(123); // x now a java type BigInteger

x == 123; // -> "true", via implicit conversion --> be careful here, because x will be implicitly be converted to JS number and may lose precision
x.equals(123); // -> "false", because comparing different data types (BigInteger / Number)
x.equals(new BigInteger(123)); // -> "true"

getBoolean()​

getBoolean(entity): boolean

Retrieves a Boolean value from a specific field in the message's data dictionary.

This method accesses a boolean value from the message using the provided data dictionary entity.

Parameters​

entity​

DataDictionaryEntity

The data dictionary entity that specifies the path to the boolean value in the message.

Returns​

boolean

The boolean value from the specified field in the message.

Example​

// Assuming we have a data dictionary entity for an "isActive" field
const isActiveEntity = dataDictionary.type.MyFormat.Detail.IS_ACTIVE;

// Get the boolean value, defaulting to false if not found
const isActive = message.getBoolean(isActiveEntity);

if (isActive) {
    print("The item is active");
} else {
    print("The item is not active");
}

getByte()​

getByte(entity): Byte

Return the Byte typed value from a message field. Important!: Please note that this method returns a Java object "Byte" (a Java native data type).

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

Returns​

Byte

Java native Byte type.

Example​

const b = message.getByte(dataDictionary.type.Detail.CSV.A_BYTE_FIELD);

getByteString()​

getByteString(entity): ByteString

Return the ByteString typed value from a message field. Important!: Please note that this method returns a "ByteString" typed value (a Java native data type).

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

Returns​

ByteString

ByteString type.

Example​

const b = message.getByteString(dataDictionary.type.Detail.CSV.FIELD);

getCharacter()​

getCharacter(entity): Character

Return a Character typed value from a message field. Important!: Please note that this method returns a "char" typed value (a Java native data type).

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

Returns​

Character

Character in Java native char type.

Example​

const c = message.getCharacter(dataDictionary.type.Detail.CSV.FIELD);

getCrc64()​

getCrc64(entity): string

Creates a CRC 64 checksum from specified node within a Message.

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity for which to create the CRC64 checksum.

Returns​

string

CRC 64 checksum

Example​

const crc64 = message.getCrc64(message.data.CSV);

getDate()​

getDate(entity): LocalDate

Return a LocalDate typed value from a message field. Important!: Please note that this method returns a "LocalDate" typed value (a Java native data type). LocalDate is a date without a time-zone in the ISO-8601 calendar system, such as "2022-12-03". This method is useful when you need to extract a date from a message field. If you need to extract a date-time with an offset from UTC/Greenwich, use the getDateTime method instead.

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

Returns​

LocalDate

A date without a time-zone in the ISO-8601 calendar system, such as "2022-12-03".

Example​

const dt = message.getDate(dataDictionary.type.Detail.CSV.A_DATE_FIELD);

getDateTime()​

getDateTime(entity): DateTime

Return a DateTime typed value from a message field.

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

Returns​

DateTime

A date-time with an offset from UTC/Greenwich in the ISO-8601 calendar system, such as "2022-12-03T10:15:30+01:00".

Example​

const dt = message.getDateTime(dataDictionary.type.Detail.CSV.FIELD);

getDecimal()​

getDecimal(entity): BigDecimal

Return a BigDecimal typed value from a message field. Important!: Please note that this method returns a "BigDecimal" typed value (a Java native data type).

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

Returns​

BigDecimal

BigDecimal in Java native char type.

Example​

const dec = message.getDecimal(dataDictionary.type.Detail.CSV.FIELD);

getDouble()​

getDouble(entity): Double

Return a Double typed value from a message field. Important!: Please note that this method returns a "Double" typed value (a Java native data type).

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

Returns​

Double

Double in Java native char type.

Example​

const dbl = message.getDouble(dataDictionary.type.Detail.CSV.FIELD);

getInt()​

getInt(entity): Integer

Return a Int typed value from a message field. Important!: Please note that this method returns a "Integer" typed value (a Java native data type).

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

Returns​

Integer

Integer in Java native char type.

Example​

const int = message.getInt(dataDictionary.type.Detail.CSV.FIELD);

getLong()​

getLong(entity): Long

Return a Long typed value from a message field. Important!: Please note that this method returns a "Long" typed value (a Java native data type).

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

Returns​

Long

Long in Java native char type.

Example​

const l = message.getLong(dataDictionary.type.Detail.CSV.FIELD);

getMessageDigest()​

getMessageDigest(algorithm?, toLowerCase?, accessorArray?): string

Returns a calculated digest for a given message

Parameters​

algorithm?​

string

Algorithm with which to calculate the digest. Currently only supprts "MD5".

toLowerCase?​

boolean = false

Set to true if digest should be lower-case only.

accessorArray?​

DataDictionaryEntity[]

Array of DataDictionaryEntity on which to calculate the digest.

Returns​

string

Example​


// Option: 1. Return digest considering complete message content.
// Digest calculation defaults to MD5 hash and no lower case.
const md5DigestFull = message.getMessageDigest();

// Option: 2. Return digest for full message content based on MD5 hash.
// Returned digest will be lower case only.
const md5DigestFullLower = message.getMessageDigest("MD5", true);

// Option: 3. Calculate digest considering specific data structures within message only.
recordAccessorForMD5 = [
    dataDictionary.type.Detail.CSV.RECORD_TYPE,
    dataDictionary.type.Detail.CSV.LAST_NAME,
    dataDictionary.type.Detail.CSV.FIRST_NAME
]

const md5Digest = message.getMessageDigest("MD5", true, recordAccessorForMD5);

getObject()​

getObject(entity): Object

Return a Object value a message field.

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

Returns​

Object

Object in Java native char type.

Example​

const o = message.getObject(dataDictionary.type.Detail.CSV.FIELD);

getStatus()​

getStatus(index): Status

Retrieves a Status by index from the list of States attached to a message. A message keeps track of related States in a Status array attached to it. This list may be empty or filled with one more States.

Parameters​

index​

number

Index of Status to retrieve.

Returns​

Status

  • Status or undefined if no Status found with that index.

Example​

// Retrieve the first Status from the list of States attached to the message.
const status = message.getStatus(0);

getString()​

getString(entity): String

Return a String typed value from a message field.

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

Returns​

String

The value as string.

Example​

const l = message.getLong(dataDictionary.type.Detail.CSV.FIELD);

hasStatusAttached()​

hasStatusAttached(severity?): void

Checks if a message has a Status attached which matches a particular Severity.

const result = message.hasStatusAttached(Severity.ERROR);

Parameters​

severity?​

Severity

Optional severity to check against.

Returns​

void

  • True, if match found, else false.

is()​

is(type): boolean

Checks if a message is of a certain type. This is typically used to check whether a message is of a certain type, or not.

Parameters​

type​

DataDictionaryEntity

Returns​

boolean

Example​

// Check if message is of a certain type
if (message.is(dataDictionary.type.Detail.CSV)) {
   ...
   // Do something
   ...
   }

numStatusAttached()​

numStatusAttached(): number

Gets the number of States Status attached.

const result = message.numStatusAttached();

Returns​

number

  • Number of States attached to the message.

pack()​

pack(): PackedMessage

Packs the message into a memory efficient format.

// Pack message
const packedMsg = message.pack();

// Unpack message
const unpackedMsg = packedMsg.unpack();

Returns​

PackedMessage

  • Packed message.

setBigInteger()​

setBigInteger(entity, value): void

Sets a BigInteger value in a message target field.

const BigInteger = Java.type("java.math.BigInteger");
bigInt = new BigInteger(123); // x now a java type BigInteger

message.setBigInteger(dataDictionary.type.Detail.CSV.FIELD, bigInt)

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

value​

Uint8Array

A native BigInteger value or a value which can be implicitly converted to such.

Returns​

void

setBoolean()​

setBoolean(entity, value): void

Sets a Boolean value in a message target field.

message.setBoolean(dataDictionary.type.Detail.CSV.FIELD, true)

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

value​

Boolean

A native Byte value or a value which can be implicitly converted to such.

Returns​

void

setByte()​

setByte(entity, value): void

Sets a Byte value in a message target field.

const Byte = Java.type("java.math.Byte");
b = new Byte(123); // b now a java type Byte

message.setByte(dataDictionary.type.Detail.CSV.FIELD, b)
// or
message.setByte(dataDictionary.type.Detail.CSV.FIELD, 7)
// or
message.setByte(dataDictionary.type.Detail.CSV.FIELD, 'X')

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

value​

string | number

A native Byte value or a value which can be implicitly converted to such.

Returns​

void

setByteString()​

setByteString(entity, value): void

Sets a ByteString value in a message target field.

const ByteString = Java.type("java.math.ByteString");
b = new ByteString("XYZ"); // b now a java type ByteString

message.setByteString(dataDictionary.type.Detail.CSV.FIELD, b)

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

value​

string

A native ByteString value or a value which can be implicitly converted to such.

Returns​

void

setCharacter()​

setCharacter(entity, value): void

Sets a Character value in a message target field.

message.setCharacter(dataDictionary.type.Detail.CSV.FIELD, 'c')

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

value​

Character

A native Character value or a value which can be implicitly converted to such.

Returns​

void

setDateTime()​

setDateTime(entity, value): void

Sets a DateTime value in a message target field.

message.setCharacter(dataDictionary.type.Detail.CSV.FIELD, "2022-12-03T10:15:30+01:00")

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

value​

DateTime

A date-time with an offset from UTC/Greenwich in the ISO-8601 calendar system, such as "2022-12-03T10:15:30+01:00".

Returns​

void

setDecimal()​

setDecimal(entity, value): void

Sets a Decimal value in a message target field. Internally represented as a Java BigDecimal. Will try to infer result from passed value.

message.setDecimal(dataDictionary.type.Detail.CSV.FIELD, 123.45)

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

value​

BigDecimal | BigInteger | Double | Integer | Long | Number | String

A value which can be represented as a Decimal.

Returns​

void

setDouble()​

setDouble(entity, value): void

Sets a Double value in a message target field. Internally represented as a Java Double. Will try to infer result from passed value.

message.setDouble(dataDictionary.type.Detail.CSV.FIELD, 123.45)

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

value​

Number | BigDecimal | BigInteger | Double | Integer | Long | String

A value which can be represented as a Double.

Returns​

void

setInt()​

setInt(entity, value): void

Sets a Int value in a message target field. Internally represented as a Java Int. Will try to infer result from passed value.

message.setInt(dataDictionary.type.Detail.CSV.FIELD, 123)

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

value​

Number | Uint8Array | BigDecimal | Double | Integer | Long | String

A value which can be represented as a Int.

Returns​

void

setLong()​

setLong(entity, value): void

Sets a Long value in a message target field. Internally represented as a Java Long. Will try to infer result from passed value.

message.setLong(dataDictionary.type.Detail.CSV.FIELD, 12345)

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

value​

BigDecimal | BigInteger | Double | Integer | Long | Number | String

A value which can be represented as a Long.

Returns​

void

setObject()​

setObject(entity, value): void

Sets a Object value in a message target field.

const obj = [1, 2, 3, 4, 5];
message.setObject(dataDictionary.type.Detail.CSV.FIELD, obj)

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

value​

Object

A value which can be represented as a Object.

Returns​

void

setString()​

setString(entity, value): void

Sets a Object value in a message target field.

message.setString(dataDictionary.type.Detail.CSV.FIELD, "XYZ")
// or simply
message.data.CSV.FIELD = "XYZ"

Parameters​

entity​

DataDictionaryEntity

DataDictionaryEntity describing the access path to the field value.

value​

Object

A value which can be represented as a String.

Returns​

void

toJson()​

toJson(): string

Returns the message in a JSON representation.

Returns​

string

Example​

const json = message.toJson();

toString()​

toString(): void

Returns the message in a string representation.

Returns​

void

Example​

stream.logInfo("Current message: " + message.toString());