ARM 4.0 Properties [ARM 4.0]

Data Structures
struct	arm_property
	defines a name value property pair. More...
struct	arm_subbuffer_app_identity
	used to specify additional identity properties for an application More...
struct	arm_subbuffer_app_context
	used to associate context properties to an application instance. More...
struct	arm_subbuffer_tran_identity
	used to specify additional identity properties for a transaction More...
struct	arm_subbuffer_tran_context
	used to associate context properties to a transaction instance. More...
Modules
	Identity properties
	Context properties
Typedefs
typedef struct arm_property	arm_property_t
	defines a name value property pair.
#define	ARM_PROPERTY_MIN_ARRAY_INDEX   0
	minimum array index for property names and values
#define	ARM_PROPERTY_MAX_ARRAY_INDEX   19
	maximum array index for property names and values
#define	ARM_PROPERTY_MAX_COUNT   20
	maximum array count for property names and values
#define	ARM_PROPERTY_NAME_MAX_CHARS   (ARM_NAME_MAX_CHARS)
	maximum characters for property names
#define	ARM_PROPERTY_NAME_MAX_LENGTH   (ARM_PROPERTY_NAME_MAX_CHARS*3+1)
	maximum number of bytes for property names
#define	ARM_PROPERTY_VALUE_MAX_CHARS   255
	maximum characters for property values
#define	ARM_PROPERTY_VALUE_MAX_LENGTH   (ARM_PROPERTY_VALUE_MAX_CHARS*3+1)
	maximum number of bytes for property values
#define	ARM_PROPERTY_URI_MAX_CHARS   4095
	maximum characters for a uri property
#define	ARM_PROPERTY_URI_MAX_LENGTH   (ARM_PROPERTY_URI_MAX_CHARS*3+1)
	maximum number of bytes for a uri property

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Detailed Description

ARM 4.0/4.1 uses two types of properties to describe applications and transactions: "identity" properties (for applications and transactions), and "context" properties (for applications and transactions). Each property consists of a name string and a value string.

They differ based on when the names and/or values are set, as shown in the following table

Type of Property	Same for all Instances	May Vary per Instance
Identity Property (applications and transactions)	Name and Value
Context Property (applications and transactions)	Name	Value

When deciding which property type to use, instrumenters should be aware of the trade-offs:

• Processing of identity properties can generally be optimized more than processing of context properties because it can be done once at registration time for both the names and the values and apply to all transaction instances.
• Processing of context property values may occur for every transaction instance. This increases overhead but it is a good practice if each transaction "flavor", where a flavor represents a different combination of properties, is a slight variation on the same type of transaction. An implementation that does not process the context properties could still provide useful reports if the performance characteristics of each flavor are similar.