Cross-Contract Calls on NEAR Protocol: Mechanisms and Use Cases

Anton Ioffe - March 25th 2024 - 6 minutes read

In the rapidly evolving landscape of blockchain technology, the NEAR Protocol emerges as a groundbreaking platform, fostering innovation and expanding the horizons of decentralized application (dApp) capabilities. At the heart of this transformation lies the intricate yet fascinating world of cross-contract calls—a feature that propels the complexity and functionality of dApps to unprecedented heights. This article embarks on a comprehensive journey through the mechanics and marvels of cross-contract calls within the NEAR ecosystem. From a technical deep dive into the execution process to exploring a myriad of real-world applications that redefine what decentralized systems can achieve, we'll navigate the challenges and considerations that developers face, shedding light on this pivotal aspect of dApp development. Whether you're a seasoned developer or a curious enthusiast, prepare to delve into the intricacies of cross-contract calls and discover how they are shaping the future of the decentralized web.

The Basics of Cross-Contract Calls

Cross-contract calls on the NEAR Protocol signify a crucial advancement in the realm of decentralized applications (dApps), enabling distinct smart contracts to seamlessly interact and communicate within a unified ecosystem. At their core, cross-contract calls allow a smart contract to invoke methods of another contract, thereby fostering a collaborative environment where contracts can extend their functionality and leverage the capabilities of one another. This interoperability is pivotal for building complex dApps on the blockchain, as it permits a decentralized network of contracts to work in concert, achieving outcomes that a singular contract could not accomplish independently.

The mechanism powering cross-contract calls on NEAR is fundamentally different from the traditional blocking calls seen in other blockchain platforms. NEAR employs a non-blocking, asynchronous model where calls between contracts are handled through promises. These promises encapsulate the action of a method call and its associated arguments, and a contract creates a new promise when it needs to call a method on another contract. This model allows multiple contracts to interact without waiting for each other’s processes to complete, thus enhancing the efficiency and speed of dApp operations on the network. It is this asynchronous promise-based approach that sets the NEAR Protocol apart, offering developers the flexibility to craft more dynamic and responsive decentralized applications.

Furthermore, handling these cross-contract calls involves keeping track of the promises and ensuring that the state changes are appropriately managed, especially in cases where a call does not succeed. Smart contracts on NEAR are thus designed with the capability to roll back state changes or perform specific actions based on the success or failure of these promise-based interactions. This model requires a thoughtful approach to contract design, where developers must anticipate the various outcomes of cross-contract calls and program their contracts to respond accordingly. The architecture not only promotes robust dApp development but also underlines the maturity of the NEAR ecosystem in accommodating complex interactions within its blockchain infrastructure.

Executing Cross-Contract Calls: Technical Deep Dive

When executing cross-contract calls on the NEAR Protocol, the process initiates with one contract dispatching a call to another, specifying the method to be invoked along with any necessary arguments. This initial step consumes a portion of the gas allotted for the transaction. It's imperative for developers to attach sufficient gas to these calls to ensure their completion; a misunderstanding or misjudgment in gas allocation can result in failed transactions due to out-of-gas errors. Additionally, since the NEAR Platform operates on a model that caps the total gas a transaction can consume, strategic gas management becomes a critical skill, ensuring that complex call graphs do not inadvertently exceed platform limits.

Upon successful execution of the called method in the target contract, a callback mechanism is employed to inform the originating contract of the outcome—whether it’s a success or failure—along with any return values. The mechanism of callbacks is pivotal, as it allows for the execution flow to return to the original caller, enabling it to respond accordingly based on the result of the cross-contract interaction. This step requires careful handling of the callback function to parse and act on the returned data or error states effectively, adding a layer of complexity in handling transaction outcomes within smart contract logic.

Ensuring security during these interactions is paramount; developers must meticulously validate both the input received before dispatching a call and the data returned by the callback. This involves assertions to verify contract addresses, method names, and the integrity of arguments to mitigate risks of interacting with malicious or erroneous contracts. Furthermore, contracts themselves must be designed to gracefully handle failures in cross-contract calls, implementing strategies for state rollback or compensation logic as needed to maintain the contract's integrity and the user's assets secure. Through mastering these technical nuances, developers can leverage cross-contract calls to build sophisticated and collaborative features within the NEAR ecosystem.

Use Cases and Applications

In the realm of Decentralized Finance (DeFi), cross-contract calls on the NEAR Protocol have paved the way for more integrated and robust financial applications. By enabling smart contracts to interact with each other, developers can create composite financial services that were previously challenging to implement. For instance, a lending application can seamlessly interact with a liquidity pool and a pricing oracle contract to provide real-time, competitive loan rates. This interoperability allows for the creation of complex DeFi products, such as yield farming strategies that automatically move assets between protocols to optimize returns, or decentralized autonomous organizations (DAOs) that aggregate community votes to manage assets in a decentralized fund.

The gaming sector also benefits significantly from cross-contract calls, where the technology brings to life intricate gaming ecosystems and in-game economies. Games built on NEAR can utilize cross-contract calls to manage in-game assets represented as non-fungible tokens (NFTs), allowing for the seamless transfer, lending, or trading of these assets across different game environments or marketplaces. Moreover, gaming platforms can leverage this functionality to implement decentralized autonomous guilds where players can collectively make decisions, manage shared assets, and distribute rewards based on smart contract rules, creating a truly decentralized gaming experience.

Asset management and tokenization platforms on NEAR harness cross-contract calls to facilitate the fractionalization of real-world assets, making them more accessible to a broader audience. By breaking down high-value assets like real estate or art into tradable tokens, these platforms can democratize investment opportunities. Cross-contract calls enable the smooth operation of these platforms by allowing various contracts, such as those governing ownership records, compliance checks, and marketplace transactions, to interact seamlessly. This ability ensures that transactions are secure, compliant with regulations, and executed efficiently, offering a transparent and trustworthy framework for digital asset management.

Challenges and Considerations

Implementing cross-contract calls presents numerous technical hurdles, especially when it comes to debugging. Due to the asynchronous nature of these calls, tracing the flow of execution or identifying the source of an error can be significantly more complex compared to traditional synchronous function calls. Debugging across contracts involves tracking the promises and managing the state changes, which demands a high level of precision and understanding of the underlying architecture. This inherent complexity makes it challenging for developers to ensure the robustness of their applications, requiring them to develop sophisticated monitoring and error-handling mechanisms to catch and respond to failures effectively.

Another critical consideration is the optimization of gas usage, a limited and fee-incurring resource on the NEAR protocol. Cross-contract calls consume gas not only for the execution of the called function but also for data storage and retrieval operations, making efficient gas management crucial. Developers must carefully allocate and manage gas to prevent out-of-gas errors that can lead to failed transactions or incomplete execution. This necessitates a strategic approach to coding, such as minimizing the amount of data passed between contracts and optimizing smart contract code to reduce gas consumption.

Ensuring call security also poses a significant challenge. Since cross-contract calls enable contracts to interact with one another, they open up potential vectors for security vulnerabilities such as reentrancy attacks or unauthorized access. It’s vital for developers to validate input and output data meticulously and employ security patterns to safeguard against such vulnerabilities. Moreover, the delegation of calls between contracts requires a stringent verification mechanism to prevent malicious contracts from exploiting the system. These challenges underscore the importance of comprehensive testing, secure coding practices, and continuous monitoring to maintain the integrity and security of applications built on the NEAR Protocol, fostering a proactive approach towards identifying and mitigating potential security risks.


The article explores the concept of cross-contract calls on the NEAR Protocol, highlighting its significance in decentralized application development. It delves into the technical mechanics of cross-contract calls, emphasizing the non-blocking, asynchronous model employed by NEAR and the challenges developers face in managing state changes and ensuring transaction success. The article also showcases the diverse use cases and applications of cross-contract calls, including in decentralized finance, gaming, and asset management. It concludes by discussing the challenges and considerations associated with implementing cross-contract calls, particularly in debugging, gas optimization, and security. Key takeaways include the transformative potential of cross-contract calls in building complex and collaborative decentralized systems and the need for developers to master the technical nuances and security practices surrounding their implementation.