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CBL: Compact Encoding of JSON-LD Data using CBOR and Bitmaps for Web of Things

Prudhvi Gudla, Kamal Singh

TL;DR

This work introduces CBL, a compact encoding scheme for JSON-LD data in the Web of Things by combining CBOR, a re-indexation dictionary, and a bitmap-based structure with a delta-encoded list of key-value indices. By leveraging a static dictionary of common terms and a dynamically delta-encoded re-indexation dictionary, CBL significantly reduces network overhead for constrained IoT devices, outperforming existing CBOR-LD baselines and even CBOR-LD-OPT without relying on gzip. The approach also uses a bitmap to efficiently encode JSON-LD structures and a carefully width-encoded list of indices to minimize bit use. Across six SSN-based JSON-LD examples, CBL achieves up to 95.5% savings and demonstrates robust performance improvements over prior methods, with ablation studies highlighting the importance of delta encoding and the full encoding pipeline for maximizing compression.

Abstract

The concept of Web of Things (WoT) merges web technologies with knowledge graphs in the context of Internet of Things. Given its widespread adoption in representing and exchanging structured data online, JSON-LD could be an effective format for WoT. Nevertheless, its verbose nature may present challenges for resource-constrained IoT devices with limited bandwidth and memory capacities. In this paper, we present a novel approach to compactly represent JSON-LD data using the Concise Binary Object Representation (CBOR) and bitmaps. Our proposed method is named as CBL which stands for CBOR, Bitmap and List of Key-value pairs. CBL leverages the ideas from CBOR and HDT to achieve an efficient encoding of JSON-LD data. Results demonstrate that our approach provides savings up to 95.1% in terms of network overhead. This could be especially beneficial for IoT devices exchanging data over wireless networks. Moreover, our approach is more efficient than the current approach known as CBOR-LD, which is used to compact JSON-LD data.

CBL: Compact Encoding of JSON-LD Data using CBOR and Bitmaps for Web of Things

TL;DR

This work introduces CBL, a compact encoding scheme for JSON-LD data in the Web of Things by combining CBOR, a re-indexation dictionary, and a bitmap-based structure with a delta-encoded list of key-value indices. By leveraging a static dictionary of common terms and a dynamically delta-encoded re-indexation dictionary, CBL significantly reduces network overhead for constrained IoT devices, outperforming existing CBOR-LD baselines and even CBOR-LD-OPT without relying on gzip. The approach also uses a bitmap to efficiently encode JSON-LD structures and a carefully width-encoded list of indices to minimize bit use. Across six SSN-based JSON-LD examples, CBL achieves up to 95.5% savings and demonstrates robust performance improvements over prior methods, with ablation studies highlighting the importance of delta encoding and the full encoding pipeline for maximizing compression.

Abstract

The concept of Web of Things (WoT) merges web technologies with knowledge graphs in the context of Internet of Things. Given its widespread adoption in representing and exchanging structured data online, JSON-LD could be an effective format for WoT. Nevertheless, its verbose nature may present challenges for resource-constrained IoT devices with limited bandwidth and memory capacities. In this paper, we present a novel approach to compactly represent JSON-LD data using the Concise Binary Object Representation (CBOR) and bitmaps. Our proposed method is named as CBL which stands for CBOR, Bitmap and List of Key-value pairs. CBL leverages the ideas from CBOR and HDT to achieve an efficient encoding of JSON-LD data. Results demonstrate that our approach provides savings up to 95.1% in terms of network overhead. This could be especially beneficial for IoT devices exchanging data over wireless networks. Moreover, our approach is more efficient than the current approach known as CBOR-LD, which is used to compact JSON-LD data.
Paper Structure (14 sections, 2 figures, 5 tables)

This paper contains 14 sections, 2 figures, 5 tables.

Table of Contents

  1. Introduction
  2. Background and Related work
  3. JSON-LD
  4. Related works on compact representations
  5. CBOR-LD
  6. CBOR, Bitmap, and List (CBL)
  7. CBOR Encoded Re-indexation Dictionary
  8. Bitmap
  9. List of Key-Value Pair Indices
  10. Evaluation
  11. Ablation Studies
  12. Discussion
  13. Conclusion
  14. Acknowledgements

Figures (2)

  • Figure 1: JSON-LD to CBOR-LD raj2024poster
  • Figure 2: CBL approach as compared to CBOR-LD approach. For CBL, note that key-value indices below point to items in the dictionary, such as shown for value index 0 pointing to 3121. Also the key indices from 0 to 5 are implied to be @id, @value.. etc. and hence are not even sent in the dictionary.