# Processing This section covers Benthos processors for data transformation and message handling. Processors allow you to modify, filter, and enrich messages as they flow through your data pipelines. ## Available Processors * [**Tag Processor**](/benthos-umh/processing/tag-processor.md) - Optimized for processing tags and time series data, converting them to the UMH data model within the `_historian` data contract. Provides automatic message formatting, metadata generation, and structured processing stages. * [**Classic to Core Processor**](/benthos-umh/processing/classic-to-core-processor.md) - Converts UMH Historian Data Contract format messages into Core format, following the "one tag, one message, one topic" principle. * [**Downsampler**](/benthos-umh/processing/downsampler.md) - Reduces time-series data volume by filtering out insignificant changes using configurable algorithms. Integrates with UMH data pipelines to compress historian data while preserving significant trends. * [**Topic Browser**](/benthos-umh/processing/topic-browser.md) - **\[Internal]** Transforms UMH messages into structured data for the Topic Browser interface. Extracts hierarchical topic information and event data to enable real-time topic exploration, metadata search, and debugging in the Management Console. * [**Stream Processor**](/benthos-umh/processing/stream-processor.md) - Collects timeseries data from multiple UNS sources and generates transformed messages using JavaScript expressions. Implements dependency-based evaluation where static mappings are evaluated on every message while dynamic mappings only evaluate when their dependencies are received. * [**Node-RED JavaScript Processor**](/benthos-umh/processing/node-red-javascript-processor.md) - Provides full control over payload and metadata through custom JavaScript code. Use this processor when you need complex transformations, conditional logic, or custom processing beyond standard tag handling. * [**More Processors**](https://docs.redpanda.com/redpanda-connect/components/processors/about/) - Additional built-in processors available in Benthos/Redpanda Connect for various data processing needs. ## Which Processor to Choose? * Use **Tag Processor** when working with structured time series data that needs to conform to the UMH data model * Use **Classic to Core Processor** when migrating from legacy UMH Historian Data Contract format to modern Core format * Use **Downsampler** after tag\_processor to reduce data volume while preserving important changes in time-series data * Use **Topic Browser** (internal) when implementing systems that need to consume and display UMH topic hierarchies and event streams * Use **Stream Processor** when you need to combine data from multiple UNS sources with state management, perform complex JavaScript transformations, and generate new UMH topics based on a model/version data contract * Use **Node-RED JavaScript Processor** when you need maximum flexibility and custom processing logic * Explore the **additional processors** for specific use cases like JSON manipulation, HTTP requests, caching, and more --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.umh.app/benthos-umh/processing.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.