Introduction

Variables are assigned constant values and expressions. This applies to:

• JS7 - Job Resources
• JS7 - Job Environment Variables
• JS7 - Order Variables
• Node Arguments
• Job Arguments

Expressions are a means to dynamically calculate values for variables. Consider that names of variables are case-sensitive.

Examples:

• true
• 1
• "some string"
• $variable
• $returnCode <= 3
• $number + 1

Data Types

Boolean

The following constant values are supported: true, false

Examples:

String

Strings are written in double quotes. The control characters \t (tab), \r (CR) and \n (NL) are literally written. To suppress its special meaning the $ character is written \$. No other characters are allowed to follow the \ escape character.

Examples:

"some value"

"\t means the TAB control character"

"\r means the CR control character"

"\n means the LF control character"

"\$ means the literal character"

Number

Numeric constants are implemented as Java  BigDecimal values and allow integer and long values to be specified.

Example:

1

Operators

Comparison Operators

The operators <, <=, ==, !=, >=, > are supported.

The result of a comparison is the Boolean data type. Comparisons are available for strings and numbers. Both sides of a comparison have to use the same data type.

Should this rule not be considered and should e.g. a number be compared to a string then an Order will fail.

Example:

$var >= 199

Arithmetic Operators

Addition and Subtraction of two numbers with: +, -

Examples:

1 + 1

100 - 210

String Operators

Concatenation of two strings with the ++ operator. Should operands of type Boolean or Number be used then they are converted to String.

Example:

"abc" ++ "def"

Conversion

Convert to Number

If a value of a variable with String data type represents a number then it can be converted. Otherwise an error is raised and the affected order fails.

Example:

"123".toNumber

Convert to String

Values of the Number data type can be converted to String.

Example:

123.toString

Reading Variables

Referencing Variables

The syntax $VARIABLE, $`VARIABLE`, ${VARIABLE} or ${`VARIABLE`} is used to read the value of a variable.

• Similar to a number of Unix shells a variable can be recalled with $ or with ${}.
• Variable names can include dots, however, not at the beginning and not at the end of the variable name and not as a sequence of dots.
• Variable names with dots have to be referenced like this: $`mail.smtp.host` or ${`mail.smtp.host`}

If the variable is unknown then an error is raised and the affected Order will fail.

Variable Function

Variables can be retrieved using the function 

variable( NAME, label=LABEL, job=JOB, default=DEFAULT )

• • NAME is a string expression for the name of the variable.
  • label=LABEL (optional) is the label of an instruction for which the variable is recalled. Consider that the label is not quoted. Example: label=A.
  • job=JOB (optional) is the name of a job for which the variable is recalled. Consider that the job name is not quoted. Example: job=MYJOB.
  • default=DEFAULT (optional) specifies a default value should the variable not exist.

Consider that a call to the variable function will fail if the variable is unknown and no default value is specified.

Examples:

variable( "my_var", job=my_job )

variable( "my_var", label=my_label, default="some value" )

Built-in Variables

Built-in variables are available at the following scopes:

Workflow

• $js7WorkflowPath
  • The unique name of a workflow. Consider that the name does not include the folder location of a workflow.
• $js7WorkflowPosition
  • The position of an order in the workflow.
• $js7Label
  • The label of the current instruction for which an order is executed.
• $js7OrderId
  • The order identifier.
• $js7ControllerId
  • The Controller's identifier.

Job

• $js7JobName
  • The name of the current job for which an order is executed.
• $epochMilli
  • The number of milliseconds since January 1^st 1970 UTC.
• $returnCode
  • The numeric exit code of the current job for which an order is executed.

Build-in Functions

• env( "environment-variable", "default" )
  • The function reads the value of an existing OS environment variable. The name has to be specified in correct uppercase/lowercase spelling.
  • If the environment variable does not exist then an error is raised and the Order fails. Alternatively a default value can be specified.

  • Examples:

    Expression	env( ('JS7_AGENT_CONFIG_DIR')
    JSON	"env( 'JS7_AGENT_CONFIG_DIR' )"
    Sample Value	/var/sos-berlin.com/js7/agent/var_4445/config

    Expression	env( 'JAVA_HOME', '/usr/lib/jvm/java-1.8-openjdk' )
    JSON	"env( 'JAVA_HOME', '/usr/lib/jvm/java-1.8-openjdk' )"
    Sample Value	/usr/lib/jvm/java-1.8-openjdk

    Expression	env( 'HOSTNAME', env( 'COMPUTERNAME' ) )
    JSON	"env( 'HOSTNAME', env( 'COMPUTERNAME' ) )"
    Sample Value	2021-05-03 07:30:42

    This example assumes the $HOSTNAME environment variable to be available for Agents running on Unix or the %COMPUTERNAME% environment variable to be available for Agents with Windows.
    
    
    

• now( format='yyyy-MM-dd hh:mm:ss', timezone='Europe/Berlin' )
  • The job start date. This date can be formatted using Java date qualifiers. Optionally a time zone can be specified, by default the UTC time zone is used.

  • Examples:

    
    

    Expression	now( format='yyyy-MM-dd' )
    JSON	"now( format='yyyy-MM-dd' )"
    Sample Value	2021-05-03

    Expression	now( format='yyyy-MM-dd hh:mm:ss' )
    JSON	"now( format='yyyy-MM-dd hh:mm:ss' )"
    Sample Value	2021-05-03 07:30:42

    Expression	now( format='yyyy-MM-dd hh:mm:ssZ', timezone="Europe/Berlin" )
    JSON	"now( format='yyyy-MM-dd hh:mm:ssZ', timezone=\"Europe/Berlin\" )"
    Sample Value	2021-05-03 09:30:42+02:00

• scheduledOrEmpty( format='yyyy-MM-dd hh:mm:ss', timezone='Europe/Berlin' )
  • The date for which an orders is scheduled.
  • The date formatting options are the same as explained with the now() function.

Further Resources

• JS7 - Assignment of Variables