Frequently Asked Questions

General

What is Bondy?

Bondy is an open-source application networking platform that connects the elements of a distributed application — web and mobile apps, IoT devices, and backend microservices — combining event mesh and service mesh capabilities in a single protocol.

Read more about Bondy in the What is Bondy section.

What is WAMP?

The Web Application Messaging Protocol (WAMP) is an open, routed protocol for polyglot distributed applications with all application agents connecting to a WAMP Router that performs message routing between them. WAMP unifies the two most important communication patterns under a single protocol: Publish-Subscribe and Routed Remote Procedure Calls.

Read more about WAMP in the What is WAMP section.

How is WAMP different than other messaging technologies?

In short: WAMP unifies Remote Procedure Calls (RPC) and Publish & Subscribe and offers a peer-to-peer programming model.

In general, WAMP differs from other messaging platforms in that it natively (and by design) provides an implementation of routed Remote Procedure Calls (RPC) together with Publish & Subscribe.

As its name implies, Publish & Subscribe offers at most once semantics a.k.a fire-and-forget, whereas other messaging platforms provide stronger message delivery guarantees e.g. at least once and exactly once semantics.

For a further comparison with other products and technologies we invite you to review the How is Bondy different section and the WAMP Compared article in the protocol specification website.

How is Bondy different than other WAMP routers?

See How is Bondy Different for a full comparison, covering scalability, availability, and operational simplicity.

Protocol Support

Is Bondy multi-protocol?

At its core Bondy implements the Web Application Messaging Protocol (WAMP). Learn why this is important in Why Bondy.

Bondy is also a multi-protocol router:

• The HTTP API Gateway maps arbitrary HTTP messages to WAMP messages, covering both RPC and Publish/Subscribe interactions.
• The MCP Gateway exposes WAMP procedures as tools to AI agents that speak the Model Context Protocol.
• The Broker Bridge re-publishes WAMP events to Kafka topics, and sends email through an SMTP relay.

How compliant is Bondy to WAMP?

Please find the answers to this question in the WAMP Compliance page.

Architecture

In which programming language is Bondy implemented?

Bondy is implemented in Erlang, a programming language and runtime built for concurrent, soft-real-time applications — the same runtime behind other real-time messaging platforms such as WhatsApp.

Why does Bondy use an eventually consistent model?

So that Bondy stays scalable and available through inter- or intra-datacentre connectivity disruptions.

An eventually consistent, CRDT-based backend gains little if the message routing or API gateway layer in front of it depends on strong consistency (e.g. a SQL database): a disruption at that layer takes the whole system down regardless of how available the backend is behind it. Bondy's routing layer uses the same eventually consistent model as its storage layer, so the property holds end to end.

Realms

How many realms can Bondy hold?

Bondy doesn't impose a limit on the number of realms. In principle, you can have as many as a single node can hold in memory (as part of the realm configuration is kept in memory).

Can I make an RPC call to a procedure registered in another realm?

All messages within Bondy are routed within a realm. A client with a session attached to realm A cannot send/receive messages to/from clients attached to realm B.

Data Storage

Does Bondy depend on an external database server?

No, Bondy does not depend on any external database server. Every Bondy node embeds bondy_db, a purpose-built storage and replication stack: durable tables are backed by a leveled LSM-tree store, with per-table CRDT convergence replicated across the cluster via bondy_oplog's anti-entropy protocol. See Data Storage & Replication for details.

Why does Bondy use its own embedded database?

Because we want to provide an always-on platform which is also easy to manage.

Most data entities in Bondy are resident in memory to reduce latency e.g. routing tables but some data has to be persisted and replicated e.g. security data used for authentication and authorization. Using an external database would imply not only the possibility of losing the connection to it and most probably the need to instrument a caching layer.

Can Bondy use an external database for storing its state?

No. Every Bondy node stores its state in its embedded database.

Some data entities, such as user identities, could in principle live in an external LDAP directory or database. For others, an external store would undermine the architectural trade-offs that justify Bondy's design — see the previous answer.

License

Is Bondy free to use?

Yes.

Is Bondy open-source software?

Yes. See How is Bondy licensed?.

How is Bondy licensed?

Bondy is licensed under the Apache License 2.0; review a copy of the license here.

How is this documentation licensed?

See Documentation License.

Commercial Support

Do you provide Commercial Support?

Yes, please contact us to understand the service level options.