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QMF Protocol
Use of Message Headers
Standard
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Message Properties
Message |
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Property | Use |
|---|---|
correlation-id | Used in request/response/indication sets to correlate responses and indications to their request. |
reply-to | Used in requests to indicate the address for the response. |
content-type | 'amqp/map' or 'amqp/list' |
user-id | Supplied in a request if authentication/authorization at the agent is appropriate. |
app-id | 'qmf2' |
Custom Application Headers
Application Header Key | Use |
|---|---|
method | 'request', 'response', or 'indication'. This field describes the message's role in a particular message-exchange pattern. |
qmf.opcode | QMF-specific operation code (see list below). The opcode defines what content, if any, is to be found in the message body. |
qmf.content | If the opcode is a data indication, this field indicates what kind of data will be found in the message body. |
qmf.agent | If this message is a data indication sent by an agent, this field contains the agent's name. |
QMF OpCodes
qmf.opcode field | Message Body Data Type | Description |
|---|---|---|
_agent_locate_request | QMF_QUERY_PREDICATE |
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_agent_locate_response | QMF_DATA |
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_agent_heartbeat_indication | QMF_DATA |
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_query_request | QMF_QUERY |
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_query_response | ??? |
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_subscribe_request | QMF_SUBSCRIBE |
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_subscribe_cancel_request | VOID |
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_subscribe_refresh_indication | VOID |
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_data_indication | List of <qmf.content> |
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h4 QMF Content Types
qmf.content field | Data Type | Description |
|---|---|---|
_schema_package | STRING | Schema package name |
_schema_id | SCHEMA_ID | Schema class identifier |
_schema_class | SCHEMA_CLASS | Schema class definition |
_object_id | OBJECT_ID | Managed object identifier |
_data | QMF_DATA | Data, managed and/or described or free-form |
_event | QMF_EVENT | Event |
Type Code | Name | Description |
agent | Agent Indication | Indication sent from an agent periodically or immediately upon receiving an agent-locate with matching criteria. This message is used in agent discovery and as a keep-alive/heartbeat indication. |
agent-locate | Agent Locate Indication | Indication sent from a console when the console wishes to discover agents in the network. This message may contain a selector indicating which subset of all agents it wishes to discover. |
response | Response | General-purpose response to a request. A response message is always correlated to a specific request and is sent to the reply-to of the request. A response may optionally contain a structured exception or it may optionally contain a list of values (i.e. output arguments from a method call). |
schema-query | Schema Query Request | A request sent by a console to an agent to discover information about the schemata of data offered by the agent. A schema query may request a list of packages (i.e. namespaces), a list of schema keys, or full schema details from the agent. |
schema | Schema Indication | Indication sent from an agent either to announce newly added schema information or as a side effect of having received a schema query request from a console. |
get-query | Get Query Request | A request sent from a console to an agent to get data from the agent. Generally, a get query is used to access managed objects owned by the agent. This message is extensible such that an agent may offer advanced query capabilities (SQL, Reporting, etc.) to consoles that know how to use the capabilities. |
managed-object | Managed Object Indication | Indication sent from an agent as a side effect of having received a get-query or a create-subscription. Managed objects have object-identifiers, schema keys, and create/destroy timestamps in addition to their attributes. |
object | Object Indication | Indication sent from an agent as a side effect of having received a get-query. Unmanaged objects have schema keys but no object-identifiers or timestamps as they are not managed, can't be addressed, and have no lifecycle. |
data | Data Indication | Indication sent from an agent as a side effect of having received a get-query. Data has attributes only and can be used for any general purpose. |
event | Event Indication | Indication sent from an agent when the agent application raises an event. |
create-subscription | Create Subscription Request | Request sent from a console to an agent to create a subscription query. Such a query behaves like a get-query except that once the matching objects are sent, the query remains open and sends updates when matching objects are changed, added, or deleted. A subscription query has a target (not necessarily the address of the requesting console), a publishing interval to control the frequency of updates, and a time-to-live. If the subscription is not renewed after the time-to-live has expired, the subscription will be cancelled by the agent. |
cancel-subscription | Cancel Subscription Request | Request sent from a console to an agent to cancel an existing subscription query. |
renew-subscription | Renew Subscription Request | Request sent from a console to an agent to renew an existing subscription query. This causes the time-to-live timer to be reset. |
method | Method Request | Request sent from a console to an agent to invoke a method on either the agent itself or on a managed object controlled by the agent. |
Operations
Agent Announce
| No Format |
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Console Topic Agent
| | |
| | <---- Agent Indication ---- |
| <------------------------ | |
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