Node names types and keys
The majority of nodes created by patterns are Software Instances and Business Application Instances. Both node kinds have attributes name and type, and, in common with all nodes maintained by patterns, must have a key. This appendix discusses how to set those attributes in a number of scenarios. In the following scenarios, the node kind is consistently referred to as a Software Instance (SI), but equivalent suggestions apply to Business Application Instances (BAIs).
The name attribute is intended to be a human-readable summary of the identity of the node - it need not be globally unique, but it should give the reader a good idea about which instance it is.
SI on single host, uniquely identified and versioned
Scenario 1 — The SI is running on a single host. The pattern can determine a unique identity, and determine the version for each SI:
Type | The name of the product, for example, "Oracle Database" or "Apache Web Server" |
---|---|
instance | The unique instance name of the SI, for example, "TRADING_DB" or "www.example.com". |
name | A string of the form " |
key | A string of the form " |
SI on single host, uniquely identified but not versioned
Scenario 2 — The SI is running on a single host. The pattern can determine a unique identity, but cannot determine the version for each SI:
Type | The name of the product, for example, "Oracle Database" or "Apache Web Server" |
---|---|
instance | The unique instance name of the SI, for example, "TRADING_DB" or "counterexamples". |
name | A string of the form " |
key | A string of the form " |
SI versioned but not uniquely identified
Scenario 3 — Cannot determine a unique name for each SI, but can find version
Type | The name of the product, for example, "Oracle Database" or "Apache Web Server" |
---|---|
name | A string of the form " |
key | Not set. |
key_group | Not set, or set to the empty string. The system creates a suitable key embedding the type and the host's key. |
SI not versioned or uniquely identified
Scenario 4 — No unique name or version available
Type | The name of the product, for example, "Oracle Database" or "Apache Web Server" |
---|---|
name | A string of the form " |
key | Not set. |
key_group | Not set, or set to the empty string. The system will create a suitable key embedding the type and the host's key |
Product with only one instance on a host
Scenario 5 — A product that can fundamentally only have one instance running on a host
Type | The name of the product, for example, "Oracle Database" or "Apache Web Server" |
---|---|
name | A string of the form " |
key | A string of the form " |
An SI or BAI spanning multiple hosts
Scenario 6 — A Software Instance or Business Application Instance spanning multiple hosts:
Type | The name of the product, for example, "Oracle Database" or "Apache Web Server" |
---|---|
instance | In this case, the SI / BAI is composed of other SIs / BAIs. To group them together, there must be some identifying characteristic for the group. In cases where there is one global instance of the application, the instance would not be set. |
name | A string of the form " |
key | A string of the form " |
Comments
Log in or register to comment.