Pallet-Scheduler: User-Friendly Design Discussions

Introduction to Pallet-Scheduler and the Need for User-Friendly Design

The pallet-scheduler is a crucial component within the Substrate framework, offering the capability to schedule tasks for execution at predetermined times or intervals. Currently, its functionality is primarily confined to a trusted origin, typically governance, as the pallet wasn't initially designed for general user accessibility. However, there's a growing need to expand its usability to allow anyone to schedule tasks, unlocking possibilities for on-chain automation and agentic contracts. This expansion necessitates careful consideration of design choices to ensure both functionality and security. In this discussion, we delve into the challenges and potential solutions for making pallet-scheduler user-friendly, while also addressing the critical aspects of Quality of Service (QoS) and security. The goal is to explore various design options that empower users to schedule tasks effectively without compromising the stability and reliability of the blockchain.

Pallet-scheduler plays a pivotal role in the Substrate framework, enabling the scheduling of tasks for execution at specific times or intervals. Its current design, however, restricts its use to a trusted origin, usually governance, due to security considerations. This limitation hinders the potential for on-chain automation and the development of agentic contracts, where users can schedule tasks autonomously. To realize the full potential of pallet-scheduler, it's essential to explore ways to make it more user-friendly while maintaining robust security measures. This involves addressing challenges related to Quality of Service (QoS), ensuring that scheduled tasks are executed reliably and efficiently, even in the presence of malicious actors. Furthermore, design considerations must prioritize the stability and integrity of the blockchain, preventing any disruptions or vulnerabilities that could arise from unauthorized or malicious task scheduling. Therefore, the focus is on examining various design options that balance user accessibility with security, empowering users to leverage pallet-scheduler effectively while safeguarding the blockchain network.

To ensure that pallet-scheduler can be utilized by a broader audience without compromising network integrity, several critical aspects must be addressed. One of the primary concerns is Quality of Service (QoS), which dictates the reliability and efficiency of task execution. In a user-friendly design, scheduled tasks should be executed promptly and reliably, regardless of network congestion or malicious activities. This necessitates the implementation of mechanisms to prioritize task execution and prevent delays or censorship. Security is another paramount consideration. Opening up pallet-scheduler to general users introduces potential risks, such as the scheduling of malicious tasks or resource exhaustion attacks. Robust security measures are essential to mitigate these risks and ensure the stability and integrity of the blockchain. These measures may include access controls, rate limiting, and mechanisms for verifying the legitimacy of scheduled tasks. Furthermore, the design must consider the potential impact on network resources, such as storage and computational power. Efficient resource utilization is crucial to prevent performance bottlenecks and ensure the scalability of the blockchain. Therefore, careful consideration must be given to the design choices that govern task scheduling and execution, striking a balance between user accessibility, security, and resource efficiency.

Possible Designs for a User-Friendly Pallet-Scheduler

1. Upgrade the Existing Scheduler Pallet

This design approach focuses on enhancing the current pallet-scheduler to accommodate user-friendly functionality while maintaining a high level of security and Quality of Service (QoS). The core idea revolves around fortifying the pallet's resilience against malicious actors and implementing mechanisms to differentiate between trusted and untrusted origins. This involves carefully adjusting the pallet's architecture and logic to handle tasks from various sources with varying levels of priority and guarantees. By upgrading the existing pallet, we can leverage the existing codebase and infrastructure, minimizing the risk of introducing new bugs or vulnerabilities. However, this approach requires careful consideration of the potential impact on existing functionality and compatibility. It's crucial to ensure that any modifications to the pallet do not disrupt or degrade the performance of existing scheduled tasks, particularly those originating from trusted sources. Furthermore, the upgrade process must be seamless and non-disruptive to the blockchain network, avoiding any downtime or service interruptions. Therefore, a thorough analysis of the existing pallet's architecture and dependencies is essential before embarking on any upgrade efforts.

Upgrading the existing pallet-scheduler requires a strategic approach to ensure that security and Quality of Service (QoS) are not compromised. Hardening the QoS involves implementing mechanisms to guarantee the timely execution of scheduled tasks, even in the presence of malicious actors attempting to disrupt or delay them. This may include techniques such as priority scheduling, resource allocation, and rate limiting. By prioritizing tasks based on their origin and importance, the pallet can ensure that critical tasks from trusted sources are executed promptly, while less critical tasks from untrusted sources may be subject to delays or restrictions. Furthermore, hardening the QoS involves implementing safeguards against denial-of-service (DoS) attacks, where malicious actors flood the network with bogus tasks to overwhelm the scheduler. Rate limiting can help prevent DoS attacks by restricting the number of tasks that can be scheduled from a single origin within a given time period. Additionally, the pallet can implement mechanisms to detect and mitigate malicious tasks, such as those that consume excessive resources or attempt to exploit vulnerabilities. By carefully hardening the QoS, the upgraded pallet can provide a more reliable and secure scheduling service for all users, regardless of their level of trust.

Distinguishing between trusted and untrusted origins is a critical aspect of upgrading the existing pallet-scheduler. This involves modifying the pallet's logic to handle tasks differently based on their origin, assigning higher priority and guarantees to tasks originating from trusted sources. One approach is to reserve the on_init function, which allows tasks to be executed during block initialization, for trusted origins only. This ensures that critical tasks, such as those related to governance or system maintenance, can be executed promptly and reliably. Tasks from untrusted origins, on the other hand, can be executed using the on_poll or tasks API, which allows tasks to be executed during block finalization. This separation of execution contexts provides a degree of isolation between trusted and untrusted tasks, preventing malicious tasks from interfering with critical system operations. Furthermore, the pallet can implement different resource allocation policies for trusted and untrusted origins. Trusted origins may be granted higher resource limits, allowing them to schedule more tasks or tasks that consume more resources. Untrusted origins, on the other hand, may be subject to stricter resource limits to prevent resource exhaustion attacks. By carefully differentiating between trusted and untrusted origins, the upgraded pallet can provide a more secure and user-friendly scheduling service, allowing users to schedule tasks autonomously while maintaining the integrity and stability of the blockchain.

2. Make Scheduler Pallet Instantiable

This design proposes making the pallet-scheduler instantiable, allowing for the creation of multiple instances with varying configurations and security levels. This approach offers flexibility in accommodating different use cases and trust models. For example, one instance could be dedicated to governance, providing guaranteed weight and high security, while another instance could be used for user-space scheduling with no guaranteed weight and lower security requirements. This separation of instances allows for tailored configurations to meet the specific needs of each use case. The governance instance, for instance, may require strict security measures and prioritization of tasks to ensure the smooth functioning of the blockchain's governance processes. The user-space instance, on the other hand, may prioritize flexibility and ease of use, allowing users to schedule tasks with minimal restrictions. However, making the pallet instantiable also introduces complexities in terms of resource management and coordination between instances. Each instance will require its own storage space and computational resources, which must be managed efficiently to prevent resource exhaustion. Furthermore, communication and coordination between instances may be necessary in certain scenarios, adding to the complexity of the overall system. Therefore, a careful analysis of the trade-offs between flexibility and complexity is essential before implementing this design approach.

Creating an instantiable pallet-scheduler involves careful consideration of Quality of Service (QoS) guarantees for each instance. Similar to the previous design, hardening the QoS is crucial to ensure the reliability and efficiency of task execution. However, in the context of instantiable pallets, QoS guarantees must be tailored to the specific needs of each instance. The governance instance, for example, may require the highest level of QoS, ensuring that critical governance tasks are executed promptly and reliably. This may involve allocating dedicated resources and prioritizing tasks from the governance instance over those from other instances. The user-space instance, on the other hand, may have less stringent QoS requirements, allowing for more flexibility in scheduling and execution. This flexibility may come at the cost of reduced guarantees, meaning that tasks from the user-space instance may be subject to delays or interruptions if resources are scarce. Furthermore, the instantiable pallet design must address the potential for resource contention between instances. If multiple instances are competing for the same resources, such as storage or computational power, it's essential to implement mechanisms to prevent resource exhaustion and ensure fair allocation. This may involve resource quotas, priority scheduling, or other techniques for managing resource contention. By carefully tailoring QoS guarantees to the specific needs of each instance and addressing potential resource contention issues, the instantiable pallet design can provide a flexible and efficient scheduling service for a wide range of use cases.

The separation of instances in an instantiable pallet-scheduler offers several advantages in terms of security and resource management. By creating separate instances for governance and user-space scheduling, the design isolates critical governance functions from the potential risks associated with user-generated tasks. This isolation prevents malicious user tasks from interfering with governance processes, ensuring the stability and integrity of the blockchain. Furthermore, the separation of instances allows for tailored security policies to be applied to each instance. The governance instance, for example, may implement strict access controls and authentication mechanisms to prevent unauthorized access and task scheduling. The user-space instance, on the other hand, may have more relaxed security policies to facilitate user adoption and experimentation. In addition to security, the separation of instances also simplifies resource management. Each instance can be allocated a specific amount of resources, such as storage and computational power, preventing resource contention and ensuring fair allocation. This isolation of resources also makes it easier to monitor and manage the performance of each instance, allowing for proactive identification and resolution of performance bottlenecks. By carefully separating instances and tailoring security policies and resource allocation to the specific needs of each use case, the instantiable pallet design can provide a secure, flexible, and efficient scheduling service for a wide range of applications.

3. Create a New Cron Pallet

This design proposes the creation of a new pallet, specifically a cron pallet, to handle user-friendly scheduling functionalities. This approach avoids any breaking changes to the existing pallet-scheduler, preserving its current functionality and security model. A new cron pallet can be designed from the ground up to meet the specific requirements of user-space scheduling, incorporating features such as flexible scheduling options, fine-grained access controls, and resource management mechanisms. This approach offers a clean separation of concerns, allowing the existing pallet-scheduler to continue serving its original purpose while the new cron pallet caters to user-friendly scheduling needs. However, creating a new pallet also entails significant development effort, including designing the pallet's architecture, implementing its logic, and thoroughly testing its functionality and security. Furthermore, the new cron pallet must be seamlessly integrated into the existing blockchain ecosystem, ensuring compatibility with other pallets and runtime components. This integration may involve defining new APIs, data structures, and event types, adding to the complexity of the development process. Therefore, a careful assessment of the development effort and integration challenges is essential before pursuing this design approach.

Creating a new cron pallet offers the advantage of leveraging the on_poll/tasks API for task execution. This API provides a flexible and efficient mechanism for scheduling tasks to be executed during block finalization. The on_poll function allows the cron pallet to regularly check for scheduled tasks that are due for execution, while the tasks API provides a mechanism for submitting tasks to the scheduler. By utilizing this API, the new cron pallet can seamlessly integrate with the existing blockchain infrastructure and leverage its scheduling capabilities. Furthermore, the on_poll/tasks API provides a degree of isolation between the cron pallet and the core blockchain logic, preventing potential interference or security vulnerabilities. The cron pallet can independently manage its own task queue and execution logic, without directly affecting the performance or stability of other blockchain components. This isolation simplifies the development and maintenance of the cron pallet, as it can be developed and tested independently of the core blockchain logic. However, it's essential to carefully manage the resource consumption of the cron pallet to prevent performance bottlenecks or resource exhaustion. The on_poll function should be executed efficiently to minimize its impact on block finalization time, and the task execution logic should be optimized to minimize resource consumption. By carefully leveraging the on_poll/tasks API and managing resource consumption, the new cron pallet can provide a robust and efficient user-friendly scheduling service.

The creation of a new cron pallet provides an opportunity to implement fine-grained access controls and resource management mechanisms. These mechanisms are crucial for ensuring the security and stability of the blockchain in a user-friendly scheduling environment. Fine-grained access controls allow the cron pallet to restrict access to its functionalities based on user identity or roles. This prevents unauthorized users from scheduling tasks or accessing sensitive data. For example, the cron pallet can implement access control policies that allow only certain users to schedule tasks with high priority or resource limits. Resource management mechanisms, on the other hand, allow the cron pallet to control the resource consumption of scheduled tasks. This prevents malicious or poorly written tasks from consuming excessive resources, such as storage, computational power, or bandwidth. The cron pallet can implement resource quotas, rate limiting, and other techniques to ensure fair and efficient resource allocation. Furthermore, the cron pallet can implement mechanisms for monitoring resource consumption and identifying tasks that are exceeding their limits. By implementing fine-grained access controls and resource management mechanisms, the new cron pallet can provide a secure and efficient user-friendly scheduling service, preventing malicious or unintentional abuse of the blockchain resources. This ensures that the blockchain remains stable and responsive, even in the presence of user-generated tasks.

Conclusion

In conclusion, making the pallet-scheduler user-friendly opens up exciting possibilities for on-chain automation and agentic contracts. The three design options presented – upgrading the existing pallet, making it instantiable, and creating a new cron pallet – each offer unique advantages and challenges. Upgrading the existing pallet provides a straightforward approach, leveraging existing infrastructure, but requires careful attention to QoS and security. Making the pallet instantiable offers flexibility but introduces complexities in resource management. Creating a new cron pallet allows for a clean separation of concerns but entails significant development effort. The optimal choice depends on a careful evaluation of these trade-offs and the specific requirements of the blockchain ecosystem. Regardless of the chosen design, ensuring QoS, security, and efficient resource management are paramount to building a robust and user-friendly scheduling service. By prioritizing these aspects, we can empower users to leverage the power of on-chain automation while maintaining the integrity and stability of the blockchain.

For further information on blockchain technology and pallet development, consider exploring resources like the Substrate Developer Hub.