Inter-Service Referencing

Building modular service architecture by referencing resources across service commissioning files.

Inter-service referencing enables resources in one service commissioning file to depend on resources defined in other service commissioning files. This allows you to build modular, reusable services that can be composed together to create complex architectures.

By default, resources within a service commissioning file can only reference other resources in the same file. Inter-service referencing breaks this limitation, allowing you to:

• Create reusable connection definitions that multiple services can share.

• Build modular architectures where services have clear separation of concerns.

• Manage complex deployments by breaking them into smaller, focused components.

Referencing Resources Across Services

To reference a resource in another service:

!ref '${otherServiceName}::resourceId'

Where:

• otherServiceName is the service that contains the target Service ID.

• resourceId is the ID of the resource in the target service.

To reference a resource from another service:

• Do not hardcode the Service ID directly.

• Instead, use a parameter that dynamically provides the correct Service ID at runtime.

parameterName is a parameter that contains the target Service ID resourceId is the ID of the resource in the target service

For example, if you define a parameter named otherServiceName, you can reference a resource in that service as:

!ref '${otherServiceName}::resourceId'

For further details, see Service ID and Resource ID.

Service Dependency Behavior

Connectware enables advanced relationships between services. Understanding how these interdependencies behave at runtime is crucial for correct deployment and maintenance.

• Child services: Services that reference other services.

• Parent services: Services that are referenced by others.

Installation Order

• Install parent services first (recommended):

  • Service relations are created automatically during installation.

  • Both parent and child services can be installed with targetState=enabled.

  • This is the most reliable approach and avoids issues during activation.

• Install child services first (alternative):

  • Service relations are only established once the parent service becomes available and the child is enabled.

  • The dependent (child) service can only be installed with targetState=disabled.

  • Attempting to install and enable a child without its parent will fail until the parent is added. Logs in Service Manager will indicate the unresolvable reference.

For more details, see targetState.

Expected Behaviors

Following are four scenarios and how the services behave in each case:

1. All services are installed and then enabled in parents/child order.

   1. This behaves as any other set of services.

   2. Disabling a Parent Service will disable all its Child Services.

2. All services are installed and then enabled in random order.

   • Child Services will not wait on the Enabling state and the request will fail.

3. Child Services are installed first without Parent Service present.

   1. These services must be installed with targetState=disabled.

   2. Trying to enable them before the parent exists will fail, with Service Manager logs indicating the missing reference.

   3. Once the parent service is added, enabling the child succeeds and the relation is established.

4. Parents services are installed first without child presents.

   • No special behavior. When child services are later added, this behaves as cases 1 or 2.

Example

The following service commissioning files demonstrate the behaviors described above:

1. A Cybus::Container running a database

   • Service ID will be mssqldatabase

2. A Cybus::Connection connecting to the database

   • Service ID will be serviceaconnection

3. A Cybus::Endpoint using referencing to use that Connection

   • Service ID will be servicebendpoint

By deploying these, you can reproduce all the installation and dependency behaviors.

SQL Database

description: MSSQL Database
metadata:
  name: MSSQL Database

definitions:
  password: password1234!

resources:
  mssqlDatabase:
    type: Cybus::Container
    properties:
      image: mcr.microsoft.com/mssql/server
      ports:
        - '1433:1433'
      environment:
        ACCEPT_EULA: 'Y'
        SA_PASSWORD: !ref password

SQL Connection

description: MSSQL Connection
metadata:
  name: Service A Connection

parameters:
  ip_host:
    type: string
    title: IP address or hostname where Connectware is installed

definitions:
  port: 1433
  database: master
  username: sa
  password: password1234!

resources:
  mssqlConnection:
    type: Cybus::Connection
    properties:
      protocol: Mssql
      connection:
        host: !ref ip_host
        port: !ref port
        username: !ref username
        password: !ref password
        database: !ref database
        useEncryption: false

SQL Endpoint

description: Service B
metadata:
  name: Service B Endpoint

parameters:
  mssqlConnectionServiceId:
    type: string
    title: Service ID of the MSSQL Connection

resources:
  mssqlVersionB:
    type: Cybus::Endpoint
    properties:
      protocol: Mssql
      connection: !ref '${mssqlConnectionServiceId}::mssqlConnection'
      subscribe:
        query: 'SELECT @@version'
        interval: 1000