Syntax Rules

References to Message Properties

In activities within a BPL process, it may be necessary to refer to properties of the message. The rules for referring to a property are different depending on the kind of messages you are working with.

• For messages other than virtual documents, use syntax like the following:

  message.propertyname
  

  

  Or:

  message.propertyname.subpropertyname
  

  

  Where propertyname is a property in the message, and subpropertyname is a property of that property.

• For virtual documents other than XML virtual documents, use the syntax described in “Syntax Guide for Virtual Property Paths” in Ensemble Virtual Documents.

• For XML virtual documents, see the Ensemble XML Virtual Document Development Guide.

Literal Values

When you assign a value to a property, you often specify a literal value. Literal values are also sometimes suitable in other places, such as the value in a trace action.

A literal value is either of the following:

• A numeric literal is just a number. For example: 42.3

• A string literal is a set of characters enclosed by double quotes. For example: "ABD"

  Note:

  This string cannot include XML reserved characters. For details, see “XML Reserved Characters.”

  For virtual documents, this string cannot include separator characters used by that virtual document format. See “Separator Characters in Virtual Documents” and “When XML Reserved Characters Are Also Separators.”

XML Reserved Characters

Because BPL processes are saved as XML documents, you must use XML entities in the place of XML reserved characters:

To include this character...	Use this XML entity...
>	>
<	&lt;
&	&amp;
'	&apos;
"	&quot;

For example, to assign the value Joe’s "Good Time" Bar & Grill to a property, set Value equal to the following:

"Joe's "Good Time" Bar & Grill"

This restriction does not apply inside <code> and <sql> activities, because Ensemble automatically wraps a CData block around the text that you enter into the editor. (In the XML standard, a CData block encloses text that should not be parsed as XML. Thus you can include reserved characters in that block.)

Valid Expressions

When you assign a value to a property, you can specify an expression, in the language that you selected for the BPL process. You also use expressions in other places, such as the condition for an <if> activity, the value in a <trace> activity, statements in a <code> activity, and so on.

The following are all valid expressions:

• Literal values, as described in the previous section.

• Function calls (Ensemble provides a set of utility functions for use in business rules and data transformations. For details, see “Ensemble Utility Functions” in Developing Business Rules.)

• References to properties, as described in “References to Properties.”

• Any expression that combines these, using the syntax of the scripting language you chose for BPL process. Note the following:

  • In ObjectScript, the concatenation operator is the _ (underscore) character, as in:

    value='"prefix"_source.{MSH:ReceivingApplication}_"suffix"'

    In Basic, the concatenation operator is & (ampersand).

  • To learn about useful ObjectScript string functions, such as $CHAR and $PIECE, see the Caché ObjectScript Reference. For Basic equivalents, see the Caché Basic Reference.

  • For a general introduction, see Using Caché ObjectScript or Using Caché Basic.

Indirection

Ensemble supports indirection in values for the following BPL element-and-attribute combinations only:

• <call name=

• <call target=

• <sync calls=

• <transform class=

The at sign symbol, @, is the indirection operator.

For example, the <call> element supports indirection in the values of the name or target attributes. The name identifies the call and may be referenced in a later <sync> element. The target is the configured name of the business operation or business process to which the request is being sent. Either of these strings can be a literal value:

<call name="Call" target="MyApp.MyOperation" async="1"> 

Or the @ indirection operator can be used to access the value of a context variable that contains the appropriate string:

<call name="@context.nextCallName" target="@context.nextBusinessHost" async="1"> 

This book describes @ indirection syntax in the documentation of each element that supports it: <call>, <sync>, and <transform>.