Expressions

A dynamic property expression allows you to source information from other places like a custom property, another dynamic property of the Components or a property in another entity, for example, a Deployment Target or an Environment.

Syntax

• Expressions are always in curly brackets:

  {@target/custom/protocol}://{/tomcat/host}:{/tomcat/port}

  In this example you can see three expressions that are concatenated in a single property expression: an expression called protocol, and expression called host and an expression called port. These values are separated by various symbols like colons and slashes. Each expression is surrounded by curly brackets. Together, they form another separate dynamic property.

  Tip: To learn how to use curly brackets in an expression, read the section: Using Curly Brackets in Expressions.

• Other entities (Deployment Targets, Applications, Components) are referenced by: @entity type

  @target: references the Target that the Component is associated to in the Profile that is used at runtime. For example, TRG1_QA1 Tomcat

• If custom is in the property name, you know that this is the expression getting the property from the UI screen. Customs sources a value that is defined in one of the custom property fields.

  @target/custom/host: sources the value that is stored in the host field of the target UI screen.

• You can also source system properties that are found in the general category; things like name, folder, or owner. Sourcing the name of an entity can be useful if you want to name databases based on each environment. Then, when you execute the script that creates that database, the naming could use the following property:

  {@environment/system/name}: Name of the Environment - development.

  The following expression can be entered to assign a unique identifier to your database:

  {@environment/system/id}

• Other symbols can be also used, like / for URL directories.

Note: For security reasons, using/referencing “foreign” protected properties is not supported. You can define protected properties at application level and can reference them at component level to use them for component deployment Workflows.

Absolute paths

Absolute paths replace the expression with the value of another property (referenced by its full name) which is available on the same entity. If the other property is not found, a warning is logged and nothing is returned.

• /world

  Value: World

  Value after evaluation: World

• /hello_world

  Value: Hello {/world}!

  Value after evaluation: Hello World!

• /example

  Value: Example: {/hello_world}

  Value after evaluation: Example: Hello World!

• /missing

  Value: Missing One{/thousand}!

  Value after evaluation:Missing One!

  Note: If the value of the /thousand property is empty, the property is ignored in the evaluation.

Relative paths

Expressions not starting with a / searches for the variable in the same namespace.

• /database/oracle/dbname

  Value: My Oracle Database

  Value after evaluation: My Oracle Database

• /database/ms/dbname

  Value: My Microsoft Database

  Value after evaluation: My Microsoft Database

• /database/oracle/connection

  Value: Database={dbname}

  Value after evaluation: Database=My Oracle Database

• /database/ms/connection

  Value: Database={dbname}

  Value after evaluation: Database=My Microsoft Database

• /database/connection

  Value: {oracle/connection}

  Value after evaluation: Database=My Oracle Database

Double Evaluation

You can use expressions within expressions. The expressions are evaluated from inner to outer.

• /database/oracle/dbname

  Value: My Oracle Database

  Value after evaluation: My Oracle Database

• /database/ms/dbname

  Value: My Microsoft Database

  Value after evaluation: My Microsoft Database

• /use_database

  Value: oracle

  Value after evaluation: oracle

• /connection

  Value: Database={/database/{use_database}/dbname}

  Value after evaluation: Database=My Oracle Database

Note: If the types of referenced dynamic properties differ they get cast automatically to the correct type (if applicable).

Context and Related Entities

Dynamic properties can reference properties of related entities which are available at deployment time. For example, a database component may access the ip-address property of the target on which it gets installed. The component may be installed on multiple deployment targets, so the property value changes depending on the component-target combination which gets currently evaluated.

During deployment, the properties are always evaluated for a single component on a single target. Therefore the dynamic properties of the following entities can be referenced:

• component

  The Component that is currently being evaluated

• application

  The Application to which the evaluated Component belongs.

• deployment_package

  The Deployment Package which is currently being installed

• workflow

  Executed workflow

• environment

  Environment on which the deployment is executed

• target

  Target on which the Component is installed

To access the dynamic properties of a related entity, use the following expression {@[related entity]/[property name]}. If no related entity is defined in the expression, the originated context is the component. If a dynamic property that is fetched within an expression is overridden on another entity the overridden value is evaluated.

If the related entity or the property on the related entity is not found a warning gets logged and an empty string returned.

Example:

• Properties of an environment:

  • /type

    Value: prod

    Value after evaluation: prod

• Properties of a database server target within the environment

  • /db-type

    Value: oracle

    Value after evaluation: oracle

• Properties of a component that gets installed on the database server target:

  • /connect-string

    Value: provider={@target/db-type};dbname={database-name}-{@environment/type};

    Value after evaluation: provider=oracle;dbname=MyDB-prod

  • /database-name

    Value: MyDB

    Value after evaluation: MyDB

Global variables

The following global properties are available in an expression {@global/[property name]}:

• username

  Name of the user that executes the workflow

• userDepartment

  Name of the department the user belongs to

• client

  Name of the client where the user was created

• token

  Authentication token for the user that executes the workflow

• CallBackURL

  The CDA URL where the workflow execution was started

• login

  The login object that is used for the workflow execution.

• aePort

  Automation Engine port

• AeHost

  Automation Engine host

• AeSystemName

  Name of the Automation Engine system

Component Links

In addition to the predefined related entities, all linked components that are defined via Component Links can be accessed like related entities via the link name. See: Working with Component Links

Endpoints

When deploying a component to targets and the targets have a deployment handler (see Deployment Panel on targets), the properties of the component are not evaluated against each endpoint/target individually, but only once against the deployment handler. Some Actions expect information of the actual endpoints. To access information of the endpoints, use the expression {@endpoints/[property name]}. This returns the property values of all endpoints that are managed by the deployment handler that gets currently evaluated, separated with commas.

Notes:

• If the target that gets evaluated is not a CDA for other targets, @endpoints is the same as @target.
• Components are deployed directly to deployment handlers too (if the required role of the component is set accordingly).
• The endpoints are ordered by their internal IDs, which ensures a consistent order if multiple {@endpoints} expressions are used.
• The @endpoints expression creates a sub evaluation for each endpoint where each of the sub evaluation changes the @target related entity to that of the endpoint. The other related entities (for example, package, component links, and so on) would not be changed.

Using Curly Brackets in Expressions

If you want to use curly brackets in expressions, you must escape them. To do so:

1. Define a Dynamic property of type static text that contains the open bracket and another one that contains the closing bracket. For example, /cb_open = { and /cb_close = }
2. Use these Dynamic Properties in expressions wherever needed. For example, if you want a connection string to look like this:

   SQLDRIVERCONNECT=ODBCVAR=SNNNNNRN,Driver={SQL Server Native Client 11.0};Server=tcp:dbserver,1433;Database=ae_db;Uid=ae_user;PWD=--XXX;MARS_CONNECTION=Yes

   Define the dynamic property expression as follows:

   SQLDRIVERCONNECT=ODBCVAR=SNNNNNRN,Driver={/cb_open}SQL Server Native Client 11.0{/cb_close};Server=tcp:dbserver,1433;Database=ae_db;Uid=ae_user;PWD=--XXX;MARS_CONNECTION=Yes