Faisal Nawab

University of California, Irvine | UCI · Department of Computer Science

The interest in building blockchain Decentralized Applications (DApps) has been growing over the past few years. DApps are implemented as smart contracts which are programs that are maintained by a blockchain network. Building DApps, however, faces many challenges—most notably the performance and monetary overhead of writing to blockchain smart con...

In database applications involving sensitive data, the dual imperatives of data confidentiality and provable query processing are important. This paper introduces PoneglyphDB, a database system that leverages non-interactive zero-knowledge proofs (ZKP) to support both confidentiality and provability. Unlike traditional databases, PoneglyphDB enhanc...

Consensus is a fundamental problem in distributed systems, involving the challenge of achieving agreement among distributed nodes. It plays a critical role in various distributed data management problems. This tutorial aims to provide a comprehensive primer for data management researchers on the topic of consensus and its fundamental and modern app...

Blockchain and Decentralized Applications (DApps) are increasingly important for creating trust and transparency in data storage and computation. However, on-chain transactions are often costly and slow. To overcome this challenge, off-chain nodes can be used to store and compute data. Unfortunately, this introduces the risk of untrusted nodes. To...

AnyLog is a decentralized platform for data publishing, sharing, and querying IoT (Internet of Things) data that enables an unlimited number of independent participants to publish and access the contents of IoT datasets stored across the participants. AnyLog provides decentralized publishing and querying functionality over structured data in an ana...

Data regulations, such as GDPR, are increasingly being adopted globally to protect against unsafe data management practices. Such regulations are, often ambiguous (with multiple valid interpretations) when it comes to defining the expected dynamic behavior of data processing systems. This paper argues that it is possible to represent regulations su...

Non-volatile memory (NVM) technologies are widely adopted in data storage solutions and battery-powered mobile and IoT devices. Wear-out and energy efficiency are two vital challenges facing the use of NVM. In Hamming Tree, we propose a software-level memory-aware solution that picks the memory segment of where a write operation is applied judiciou...

Blockchain and Decentralized Applications (DApps) are increasingly important for creating trust and transparency in data storage and computation. However, on-chain transactions are often costly and slow. To overcome this challenge, off-chain nodes can be used to store and compute data. Unfortunately, this introduces the risk of untrusted nodes. To...

We propose Transactional Edge (TransEdge), a distributed transaction processing system for untrusted environments such as edge computing systems. What distinguishes TransEdge is its focus on efficient support for read-only transactions. TransEdge allows reading from different partitions consistently using one round in most cases and no more than tw...

The problem of distributed consensus has played a major role in the development of distributed data management systems. This includes the development of distributed atomic commit and replication protocols. In this monograph, we present foundations of consensus protocols and the ways they were utilized to solve distributed data management problems....

Consensus is the problem of making distributed nodes reach agreement. It is a basic building block that can be used in more complex distributed data management systems while retaining correctness guarantees of the state of the data and its recovery. Solving the intricacies of distributed coordination, network uncertainties, and failures in such com...

Recently, non-volatile memory (NVM) technology has revolutionized the landscape of memory systems. With many advantages, such as non volatility and near zero standby power consumption, these byte-addressable memory technologies are taking the place of DRAMs. Nonetheless, they also present some limitations, such as limited write endurance, which hin...

Recently, Non-Volatile Memory (NVM) technology has revolutionized the landscape of memory systems. With many advantages, such as non volatility and near zero standby power consumption, these byte-addressable memory technologies are taking the place of DRAMs. Nonetheless, they also present some limitations, such as limited write endurance, which hin...

Clustering aims to group unlabeled objects based on similarity inherent among them into clusters. It is important for many tasks such as anomaly detection, database sharding, record linkage, and others. Some clustering methods are taken as batch algorithms that incur a high overhead as they cluster all the objects in the database from scratch or as...

With a growing interest in edge applications, such as the Internet of Things, the continued reliance of developers on existing edge architectures poses a threat. Existing edge applications make use of edge devices that have access to limited resources. Hence, they delegate compute-intensive tasks to the third-party cloud servers. In such an edge-cl...

Emerging edge applications require both a fast response latency and complex processing. This is infeasible without expensive hardware that can process complex operations -- such as object detection -- within a short time. Many approach this problem by addressing the complexity of the models -- via model compression, pruning and quantization -- or c...

The current state-of-the-art in user mobility research has extensively relied on open-source mobility traces captured from pedestrian and vehicular activity through a variety of communication technologies as users engage in a wide-range of applications, including connected healthcare, localization, social media, e-commerce, etc. Most of these trace...

Recently, Non-Volalile Memory (NVM) technology has revolutionized the landscape or memory systems. With many advantages, such as non volatility and near zero standby power consumption, these byte-addressable memory technologies are taking the place of DRAMs. Nonetheless, they also present some limitations, such as limited write endurance, which hin...

This errata article discusses and corrects a minor error in our work published in VLDB 2019. The discrepancy specifically pertains to Algorithms 3 and 4. The algorithms presented in the paper are biased towards a commit decision in a specific failure scenario. We explain the error using an example before correcting the algorithm.

We propose WedgeChain, a data store that spans both edge and cloud nodes (an edge-cloud system). WedgeChain consists of a logging layer and a data indexing layer. In this study, we encounter two challenges: (1) edge nodes are untrusted and potentially malicious, and (2) edge-cloud coordination is expensive. WedgeChain tackles these challenges by th...

Blockchain is a decentralized technology that protects sensitive data from being controlled by a central authority and can play a vital security role in developing the Industrial Internet of Things (IIoT). Most IIoT-blockchain systems focus on optimizing consensus mechanisms, which cannot provide satisfactory scalability until addressing the inheri...

Non-volatile memory (NVM) technologies suffer from limited write endurance. To address this challenge, we propose Predict and Write (PNW), a K/V-store that uses a clustering-based machine learning approach to extend the lifetime of NVMs. PNW decreases the number of bit flips for PUT/UPDATE operations by determining the best memory location an updat...

State machine replication protocols, like MultiPaxos and Raft, are at the heart of nearly every strongly consistent distributed database. To tolerate machine failures, these protocols must replace failed machines with live machines, a process known as reconfiguration. Reconfiguration has become increasingly important over time as the need for frequ...

The basic structure of the LSM[3] tree consists of four levels (we are considering only 4 levels), L0 in memory, and L1 to L3 in the disk. Compaction in L0/L1 is done through tiering, and compaction in the rest of the tree is done through leveling. Cooperative-LSM (C-LSM) is implemented by deconstructing the monolithic structure of LSM[3] trees to...

Wide-area Edge Database (WedgeDB) span globally and store data closer to the users. We term this the Global Edge Data management problem. In such an environment, aspects such as data storage, retrieval, transaction processing, and protection from malicious actors need to be addressed by any data management system that aims to consider itself a viab...

According to YouTube statistics [1], more than 400 hours of content is uploaded to its platform every minute. At this rate, it is estimated that it would take more than 70 years of continuous watch time in order to view all content on YouTube, assuming no more content is uploaded. This raises great challenges when attempting to actively process and...

Providing security and privacy for the Internet of Things (IoT) applications while ensuring a minimum level of performance requirements is an open research challenge. Recently, Blockchain offers a promising solution to overcome the current peer-to-peer networks limitations. In the context of IoT, Byzantine Fault Tolerance-based (BFT) consensus prot...

The byzantine fault-tolerance model captures a wide-range of failures-common in real-world scenarios-such as ones due to malicious attacks and arbitrary software/hardware errors. We propose Blockplane, a middleware that enables making existing benign systems tolerate byzantine failures. This is done by making the existing system use Blockplane for...

Data storage in the Cloud needs to be scalable and fault-tolerant. Atomic commitment protocols such as Two Phase Commit (2PC) provide ACID guarantees for transactional access to sharded data and help in achieving scalability. Whereas consensus protocols such as Paxos consistently replicate data across different servers and provide fault tolerance....

The efficient processing of video streams is a key component in many emerging Internet of Things (IoT) and edge applications, such as Virtual and Augmented Reality (V/AR) and self-driving cars. These applications require real-time high-throughput video processing. This can be attained via a collaborative processing model between the edge and the cl...

In this paper, we propose Dynamic Paxos (DPaxos), a Paxos-based consensus protocol to manage access to partitioned data across globally-distributed datacenters and edge nodes. DPaxos is intended to implement a State Machine Replication component in data management systems for the edge. DPaxos targets the unique opportunities of utilizing edge compu...

Cloud-based data-intensive applications have to process high volumes of transactional and analytical requests on large-scale data. Businesses base their decisions on the results of analytical requests, creating a need for real-time analytical processing. We propose Janus, a hybrid scalable cloud datastore, which enables the efficient execution of d...

Global-scale data management (GSDM) empowers systems by providing higher levels of fault-tolerance, read availability, and efficiency in utilizing cloud resources. This has led to the emergence of global-scale data management and event processing. However, the Wide-Area Network (WAN) latency separating data is orders of magnitude larger than conven...

Trends detection in social networks is possible via a multitude of models with different characteristics. These models are pre-defined and rigid which creates the need to expose the social network graph to data scientists to introduce the human-element in trends detection. However, inspecting large social network graphs visually is tiresome. We tac...

Geo-replication is the process of maintaining copies of data at geographically dispersed datacenters for better availability and fault-tolerance. The distinguishing characteristic of geo-replication is the large wide-area latency between datacenters that varies widely depending on the location of the datacenters. Thus, choosing which datacenters to...

Cross datacenter replication is increasingly being deployed to bring data closer to the user and to overcome datacenter outages. The extent of the influence of wide-area communication on serializable transactions is not yet clear. In this work, we derive a lower-bound on commit latency. The sum of the commit latency of any two datacenters is at lea...

Transaction time databases can be put to a number of valuable uses, auditing, regulatory compliance, readable backups, and enabling multi-version concurrency control. While additional storage for retaining multiple versions is unavoidable, compression and the declining cost of disk storage largely removes that impediment to supporting multi-version...

With large elastic and scalable infrastructures, the Cloud is the ideal storage repository for Big Data applications. Big Data is typically characterized by three V's: Volume, Variety and Velocity. Supporting these properties raises significant challenges in a cloud setting, including partitioning for scale out; replication across data centers for...

In this paper we study the interactions of TCP and IEEE 802.11 MAC in Wireless Mesh Networks (WMNs). We use a Markov chain to capture the behavior of TCP sessions, particularly the impact on network throughput due to the effect of queue utilization and packet relaying. A closed form solution is derived to numerically determine the throughput. Based...

The past decade has witnessed an increasing adoption of cloud database technology, which provides better scalability, availability, and fault-tolerance via transparent partitioning and replication, and automatic load balancing and fail-over. However, only a small number of cloud databases provide strong consistency guarantees for distributed transa...

The past decade has witnessed an increasing adoption of cloud database technology, which provides better scalabil-ity, availability, and fault-tolerance via transparent parti- tioning and replication, and automatic load balancing and fail-over. However, only a small number of cloud databases provide strong consistency guarantees for distributed tra...

Preserving the integrity of application data across updates in the presence of failure is an essential function of computing systems, and byte-addressable non-volatile memory (NVM) broadens the range of fault-tolerance strategies that implement it. NVM invites programs to manipulate durable data directly via load and store instructions, but overhea...

Web service providers have been using NoSQL datastores to provide scalability and availability for globally distributed data at the cost of sacrificing transactional guarantees. Recently, major web service providers like Google have moved towards building storage systems that provide ACID transactional guarantees for globally distributed data. For...

Over the past few years, cloud computing and the growth of global large scale computing systems have led to applications which require data management across multiple datacenters. Initially the models provided single row level transactions with eventual consistency. Although protocols based on these models provide high availability, they are not id...

We present a framework for concurrency control and availability in multi-datacenter datastores. While we consider Google's Megastore as our motivating example, we define general abstractions for key components, making our solution extensible to any system that satisfies the abstraction properties. We first develop and analyze a transaction manageme...

In this paper we study the interactions of TCP and IEEE 802.11 MAC in Wireless Mesh Networks (WMNs). We use a Markov chain to capture the behavior of TCP sessions, particularly the impact on network throughput performance due to the effect of queue utilization and packet relaying. A closed form solution is derived to numerically determine the throu...

We present a framework for concurrency control and availability in multi-datacenter datastores. While we consider Google's Megastore as our motivating example, we define general abstractions for key components, making our solution extensible to any system that satisfies the abstraction properties. We first develop and analyze a transaction manageme...

We propose TMAC, a timestamp-ordered MAC protocol for Wireless Mesh Networks (WMNs). TMAC extends CSMA/CA by scheduling data packets based on their age. Prior to transmitting a data packet, a transmitter broadcasts a request control message appended with a timestamp to a selected list of neighbors. It can proceed with the transmission only if it re...