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Secure Low-Latency Interactive Messaging SLIM

Coordinate SLIM (Secure Low-Latency Interactive Messaging) is a messaging/transport framework built for the AGNTCY project, intended to serve as the secure, scalable transport layer underneath higher-level agent protocols such as A2A and MCP [1]. It solves a gap those protocols leave open: neither A2A nor MCP specifies a low-latency, group-aware, end-to-end-encrypted messaging transport; SLIM supports request-response, publish-subscribe, fire-and-forget, and streaming interaction patterns, and builds in authentication, authorization, and end-to-end (MLS) encryption at the transport layer [2]. Architecturally it splits into a Data Plane (pure hierarchical-name-based packet routing, content-blind), a Session Layer (reliable delivery, end-to-end MLS encryption, group membership), and a Control Plane (configuration, monitoring, orchestration) — letting lightweight routing nodes run only the data plane while applications carry the full stack via language bindings (Python, Go, .NET, Java, Kotlin) [1].

Overview

SLIM does not define agent discovery, identity, or task semantics itself — those are the roles of A2A/MCP and AGNTCY's separate directory/identity components; SLIM's own README frames itself purely as the transport underneath those protocols [1].

Current state: the agntcy/slim repository was created 2025-02-05, is Apache-2.0 licensed, and is actively maintained (CI, code coverage, and OpenSSF Scorecard badges all present and green as of this check) [1]. AGNTCY itself — the umbrella project SLIM belongs to — was donated by Cisco to the Linux Foundation, with Dell Technologies, Google Cloud, Oracle, and Red Hat joining as formative members, to standardize open multi-agent-system infrastructure including discovery, identity, messaging (SLIM), and observability [2]. A SLIM specification has also been filed as an individual IETF Internet-Draft, draft-mpsb-agntcy-slim-00, though it is not yet a working-group document — this record treats the Linux Foundation/AGNTCY project as SLIM's primary governance home given that the code, documentation, and formative-member structure all live there, and marks track as linux-foundation rather than ietf accordingly. Implementations exist and ship as bindings across five languages plus integrations for A2A and MCP transport (slim-a2a-python, slim-mcp-python) and OpenTelemetry [1]. What is unresolved: no independently measured adoption count was found; this is a genuinely new record added during this verification pass per the coordinator's occupant-diff instruction, and its exact relationship to the IETF draft (same authors? formally submitted by the AGNTCY project?) was not further disambiguated in this pass.

Discovery and probe

none · none

none none — SLIM is a session/routing protocol operated by a data-plane node over its own wire format, not a document served at a fixed well-known HTTP path; no origin-fetchable probe was identified
parse:     not applicable: there is no HTTP response to parse; presence would instead be inferred from a target's published SLIM node configuration or its listed use of the slim-a2a-python / slim-mcp-python bindings
on absent: not applicable — SLIM has no well-known discovery surface as of this verification; see summary_md

Not probed live: not-http. SLIM is a transport operated by data-plane nodes on its own wire protocol.

History

Instances

Every instance with its source is listed on the instances page.

See also

References

  1. SLIM (Secure Low-Latency Interactive Messaging) is described by its own README as a next-generation communication framework providing the secure, scalable transport layer for AI agent protocols like A2A and MCP, with a Data Plane, Session Layer, and Control Plane architecture; the repository is Apache-2.0 licensed and was created 2025-02-05 under the agntcy GitHub org. — https://raw.githubusercontent.com/agntcy/slim/main/README.md (2026-09-05) VERIFIED
  2. Cisco donated the AGNTCY project, which SLIM belongs to, to the Linux Foundation; formative members named include Cisco, Dell Technologies, Google Cloud, Oracle, and Red Hat, and the project covers discovery, identity, messaging, and observability for multi-vendor AI agents, with SLIM as its messaging-transport protocol. — https://www.techzine.eu/blogs/infrastructure/133408/cisco-donates-agntcy-to-linux-foundation-internet-of-agents-on-its-way/ (2026-09-05) VERIFIED
  3. A SLIM specification has also been filed at the IETF as an individual draft, draft-mpsb-agntcy-slim-00, "Secure Low-Latency Interactive Messaging (SLIM)." — https://www.ietf.org/archive/id/draft-mpsb-agntcy-slim-00.html (2026-09-05) REPORTED

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