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This comprehensive explanation has been generated from 111 GitHub source documents. All source documents are searchable here.
Last updated: October 7, 2025
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In KERI protocol, qry is a message type abbreviation for 'query' operations that enable controllers to request information about identifier states, key events, and other protocol-relevant data from witnesses, watchers, or other KERI infrastructure components.
qry is a standardized message type identifier in the KERI (Key Event Receipt Infrastructure) protocol, serving as an abbreviation for "query". As documented in the canonical KERI/GLEIF glossary, qry represents one of several compact three-character codes used throughout the KERI message taxonomy to designate specific protocol operations.
The source materials for qry consist primarily of minimal stub entries and brief references within larger technical specifications. The term is defined tersely across multiple glossary sources:
These sources establish qry as protocol shorthand rather than a complex technical concept requiring extensive explanation. The abbreviation appears in KERI message type listings, API specifications, and protocol documentation as part of the broader message classification system.
Within KERI's message architecture, qry belongs to a family of three-character message type codes that enable efficient protocol operations. The KERI specification documents reference qry alongside other message types:
exn: Exchange messages for peer-to-peer interactionsQuery messages in KERI follow the standard message format with a t field set to "qry". The query payload typically includes:
r): Specifies the query endpoint or resource pathq): Contains query-specific data such as AID prefixes, sequence numbers, or filter criteriadt): ISO 8601 timestamp for replay attack protectionQuery operations in KERI are inherently asynchronous. When a controller sends a qry message to a witness or watcher, the response may not be immediate. The infrastructure component processes the query and returns a rpy (reply) message when the requested data is available. This pattern supports KERI's indirect mode where participants may be intermittently connected.
Implementations should consider query optimization strategies:
Query messages themselves do not require signatures in many contexts, as they are requests for publicly verifiable data. However, implementations should implement KRAM (KERI Request Authentication Method) for replay attack protection, particularly in scenarios where query access should be restricted or rate-limited.
rpy: Reply messages responding to queriesicp: Inception events creating new identifiersrot: Rotation events updating key stateixn: Interaction events for non-establishment operationsrct: Receipt messages from witnessesThis taxonomy reflects KERI's design principle of using compact, memorable codes for protocol operations, optimizing both human readability and machine processing efficiency.
The source documents show qry appearing in several technical contexts:
The KERI foundational specification references message types including queries as part of the protocol's communication framework. Controllers, validators, and infrastructure components exchange messages with type designators like qry to indicate the nature of protocol operations.
The Out-Of-Band-Introduction (OOBI) specification discusses discovery mechanisms where queries enable participants to request information about identifiers and their associated endpoints. The OOBI protocol leverages KERI's message infrastructure, including query operations, for bootstrapping trust relationships.
Various implementation documents reference qry in the context of:
The Composable Event Streaming Representation (CESR) specification establishes encoding standards for all KERI messages, including those with qry type designators. CESR's dual text-binary encoding applies to query messages as it does to all KERI protocol communications.
While qry itself is minimally documented, the source materials extensively discuss query-reply communication patterns that utilize query messages:
KERI's architecture supports asynchronous operations where:
qry type designation)rpy) returns the requested informationThis pattern enables KERI's indirect mode operations where controllers may be offline when queries are initiated, with witnesses or watchers buffering responses until the controller reconnects.
The source documents describe various scenarios where query operations facilitate information discovery:
The KERI Command-Line Interface (KLI) documentation shows query operations as fundamental to:
While specific qry message formatting isn't detailed in the stub sources, the KLI examples demonstrate the practical application of query operations in KERI implementations.
The SignifyTS tutorial materials show query patterns in credential workflows:
These examples illustrate query operations as core to KERI's client-server architecture, though the low-level message type codes are abstracted by the library interface.
The KERIA (KERI Agent in the cloud) specifications reference query handling as part of the agent's REST API, where:
The KERIA documentation establishes the agent as a query responder in KERI's distributed architecture.
The minimal documentation of qry reflects KERI's broader design philosophy:
KERI favors small, composable primitives rather than monolithic protocol elements. The qry abbreviation exemplifies this approach—a simple, memorable code that can be combined with other protocol elements to construct complex operations.
KERI messages use type designators like qry to make message intent explicit. This self-describing property enables:
The KERI whitepaper emphasizes "minimally sufficient means" as a design principle. The terse qry notation reflects this philosophy—providing just enough information to designate message type without unnecessary verbosity.
Query operations are fundamental to KEL discovery and verification. Participants query infrastructure components to:
Queries enable participants to determine the current key state of identifiers, including:
In credential systems, query operations support:
The TEL specification references query patterns for determining credential states.
Query operations contribute to KERI's duplicity detection mechanisms by:
While the stub sources don't detail qry message structure, KERI specifications establish that all messages follow standard formatting:
v): Protocol version identifiert): Set to "qry" for query messagesQuery messages in KERI infrastructure require authentication:
The KRAM specification details authentication requirements for non-interactive protocols including query operations.
Query messages utilize various transport mechanisms:
The KERI IETF specifications reference message types including queries as part of the protocol's standardization effort. The draft specifications establish:
The did:keri method specification shows how query operations integrate with W3C standards:
Trust over IP Foundation specifications reference KERI query mechanisms as part of the broader decentralized identity architecture.
The qry abbreviation represents a minimal but essential element of KERI's message taxonomy. The source documentation establishes it as:
The term's minimal documentation reflects its nature as a straightforward abbreviation rather than a complex technical concept. The qry code enables efficient designation of query operations within KERI's message infrastructure, supporting the protocol's goals of composability, self-description, and minimal sufficient means.
Understanding qry requires recognizing it as part of KERI's broader message architecture, where compact codes enable efficient protocol operations while maintaining human readability and machine processing efficiency. The abbreviation serves as a building block in KERI's distributed identity infrastructure, facilitating the query-reply patterns essential to key event discovery, state verification, and credential status checking.