Building Context-Aware Reasoning Applications with LangChain and LangSmith

By Anyscale Ray Team   

Update June 2024: Anyscale Endpoints (Anyscale's LLM API Offering) and Private Endpoints (self-hosted LLMs) are now available as part of the Anyscale Platform. Click here to get started on the Anyscale platform.

This blog post is part of the Ray Summit 2023 highlights series where we provide a summary of the most exciting talk from our recent LLM developer conference.

Disclaimer: Summary was AI generated with human edits from video transcript.

LinkKey Takeaways

Building context-aware reasoning applications is a complex but critical task in today's AI-driven world. Companies like LangChain provide tools like LangSmith to assist developers in creating these applications efficiently. In this blog post, we'll delve into the key takeaways from Harrison Chase’s Ray summit talk, the CEO of LangChain. We'll explore the challenges in building such applications, including data engineering, prompt engineering, debugging, evaluation, and collaboration among teams. This blog post will provide insights into LangChain's innovative approaches and the evolving landscape of LLM context-aware reasoning applications.

  • Context-aware reasoning applications involve connecting language models to external data sources and computation to provide relevant context for reasoning and decision making.

  • There are different types of context that can be provided, including instruction prompting, few-shot examples, retrieval/grounding, and fine-tuning. 

  • Different levels of reasoning architectures include single LLM calls, chaining, routing, state machines/automatons, and autonomous agents.

  • Key challenges in building these applications include orchestration, data engineering, prompt engineering, debugging, and evaluation. 

  • LangChain provides frameworks and utilities for orchestration, debugging, and connecting to data sources.

  • LangSmith provides tools for logging, debugging, testing, and collaboration for developing these applications.

  • Building good evaluation datasets and metrics is very application specific and requires engineering investment.

  • Collaboration between different skillsets (e.g. prompt engineering and data engineering) is an important consideration.

Building Context-Aware Reasoning Applications with LangChain and LangSmith

In today's AI-powered world, context-aware reasoning applications are at the forefront of innovation. They enable machines to understand and interact with users in a way that feels more human. However, building such applications is a complex and challenging task that involves various components, including data engineering, prompt engineering, debugging, evaluation, and collaboration among different teams.

In this blog post, we'll explore the insights and wisdom shared by Harrison Chase, the CEO and co-founder of LangChain. Harrison discusses the challenges and solutions in the development of context-aware reasoning applications, offering a deep dive into the LangChain ecosystem, including LangSmith. Let's dive into the world of context-aware reasoning applications.

LinkThe Foundation of Context-Aware Reasoning Applications

Building context-aware reasoning applications starts with understanding the critical components that drive their functionality. These applications often rely on powerful language models that process and generate natural language text. As Harrison Chase explains, it's a multifaceted process that involves:

1. Data Engineering

A significant portion of building context-aware reasoning applications is dedicated to data engineering. Developers must ensure that the language model receives the right context. Much of this context is text-based data, and it's crucial to handle data preprocessing accurately. Removing distractions like XML or HTML tags from the text is just one part of the challenge. Harrison highlights the need for connectors to various data sources and the proper formatting of data before it reaches the language model.

2. Prompt Engineering

Language models interact with users primarily through prompts. Crafting effective prompts is an art. It involves experimenting with different prompt variations and ensuring that the context provided to the model aligns with the intended output. This step often ties in with data engineering, as the data must be correctly formatted before it's incorporated into the prompt.

3. Debugging in Complex Systems

As context-aware reasoning applications scale up in complexity, debugging becomes a formidable challenge. The flow of data through these systems is intricate, with non-deterministic language models at various stages. Harrison introduces LangSmith as a solution for efficient debugging. It provides a way to visualize what goes in and out of each step in the process, allowing developers to identify and resolve issues effectively.

4. Evaluation: A Daunting Task

Evaluating the performance of context-aware reasoning applications is another hurdle. These applications often produce natural language text as output, making evaluation a unique challenge. Unlike traditional machine learning, there are no easy-to-measure metrics, and reliable ground truth data can be hard to come by. Harrison suggests the creation of custom datasets for evaluation but emphasizes that it's a demanding task. Evaluating real-time data, such as answering questions about the current temperature, poses another set of challenges. Harrison discusses various methods, including recording intermediate states and instruction sets, to facilitate evaluation in such scenarios.

LinkThe Evolving Landscape of Retrieval Mechanisms

A significant part of context-aware reasoning involves retrieval mechanisms. These mechanisms determine how applications retrieve relevant information from various sources. Harrison discusses the limitations of traditional retrieval mechanisms and the need for more advanced solutions. He points out that the ideal retrieval system remains a challenge, as it varies across applications.

LinkAdvanced Retrieval Mechanisms

Harrison introduces some advanced retrieval mechanisms developed by LangChain. These mechanisms aim to overcome the limitations of conventional retrieval approaches. Here are two notable ones:

1. Parent Document Retriever

The Parent Document Retriever is designed to bridge the gap between semantic search over small chunks of data and providing the language model with more extensive context. It retrieves larger parent documents based on semantic searches and passes these documents to the model, offering a balance between specificity and context richness.

2. Self-Query Retriever

The Self-Query Retriever is particularly useful when a query involves specific details that might not be semantically related to the primary question. It works by splitting a question into a semantic query and a metadata filter, allowing for more precise retrieval from vector databases.

Harrison emphasizes that retrieval mechanisms are still highly application-specific, and there's no one-size-fits-all solution.

LinkCollaboration in Complex Systems

As context-aware reasoning applications become more intricate, they often involve collaboration among different teams. Harrison touches on the challenges of teams working on various aspects of these systems, such as prompt engineering and data engineering. These teams may have different skill sets and objectives, making collaboration crucial.

LangChain is actively exploring solutions for improved collaboration among teams. Currently, the most common methods are using GitHub for code and prompts or Excel spreadsheets for tracking. However, Harrison acknowledges that these solutions are less than ideal, particularly for non-technical team members. LangChain is working on a collaboration hub that aims to streamline teamwork in these complex systems.


Building context-aware reasoning applications is a journey filled with challenges, but it's also one of immense potential. With the right tools and techniques, developers can create applications that truly understand and respond to users' needs. LangChain, with its innovative tools like LangSmith and its commitment to tackling the complexities of data engineering, prompt engineering, debugging, evaluation, and collaboration, is playing a significant role in advancing this field.

The key takeaways from Harrison Chase's insights are clear: Building context-aware reasoning applications is a multifaceted process that requires careful attention to data, prompts, debugging, evaluation, and collaboration. Retrieval mechanisms continue to evolve, and the field remains dynamic. While there are no universal solutions, LangChain's innovative approaches and tools are poised to shape the future of context-aware reasoning applications.

In the ever-evolving landscape of AI and ML, context-aware reasoning applications will continue to be at the forefront of innovation, and LangChain is playing a crucial role in this exciting journey.

Sign up now for Anyscale endpoints and get started fast or contact sales if you are looking for a comprehensive overview of the Anyscale platform. 

Ready to try Anyscale?

Access Anyscale today to see how companies using Anyscale and Ray benefit from rapid time-to-market and faster iterations across the entire AI lifecycle.