> For the complete documentation index, see [llms.txt](https://monobridge.gitbook.io/monobridge/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://monobridge.gitbook.io/monobridge/anycall/2.2-architecture-of-mono-bridge-router-protocol.md).

# 2.2 Architecture of Mono Bridge Router Protocol

Mono is a new generation generic cross - chain messaging protocol featuring openness and public accessibility, which is designed to boost the development and deployment of cross-chain Dapps. As the underlying infrastructure in the era of multi-chain ecosystem, anyCall has the following key functions:

1. Generic cross-chain messaging anyCall supports the transmission of generic messages including transaction status and other data, business logic, etc.
2. Cross-chain call of contracts anyCall supports cross-chain contract calls by any Dapps through the "anyCall" interface deployed on the source chain and the "anyExec" interface deployed on the target chain.
3. Decentralization The decentralized trust mechanism of the underlying fastMPC ensures the decentralized nature of anyCall.
4. Openness and public accessibility Any Dapp can develop and deploy its own cross-chain Dapp by calling the interface of anyCall deployed on two or more chains in the multi-chain environment. In other words, anyCall has built a publicly accessible generic messaging channel for these chains. These chains either of the same or different technological systems are connected together to form a multi-chain application environment for cross-chain Dapps.

MonoB consists of an off-chain trust mechanism (at the lower layer) and an on-chain call/trigger API (at the upper layer), as shown in Figure 4.

<figure><img src="/files/poYC1jVw1Dx23oNHye14" alt=""><figcaption></figcaption></figure>

* &#x20;Off-chain trust mechanism The off-chain trust mechanism validates the messages from the source chain for consensus, performs target chain addressing according to the logic specified by the cross-chain Dapp, and triggers corresponding operations.&#x20;
* &#x20;On-chain call/trigger API There is a trigger API on the source chain and a call API on the target chain. Once the Dapp triggers the off-chain trust mechanism through the trigger API on the source chain, the off-chain trust mechanism will initiate the validation for consensus through the smart contract deployed on the source chain, and subsequently, the call API deployed on the target chain will complete the call of the contract designated by the Dapp. AnyCall provides the interfaces to be called when developing cross-chain Dapps, namely the "anyCall" interface on the source chain and the "anyExec" interface on the target chain. In other words, anyCall becomes a generic cross-chain messaging protocol for cross-chain contract calls.