BatchRefine adds batch processing capabilities to OpenRefine
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Latest commit bbca1e3 Dec 14, 2016 @ktk ktk committed on GitHub Clarified JSON file size limit

BatchRefine Build Status

P3-BatchRefine provides methods to run OpenRefine in batch mode. It does so by providing a collection of wrappers (called backends) and a distribution layer on top of OpenRefine.

Clients can access the backends by two ways: using a commandline client or using an HTTP API based on the Fusepool P3 transformer API. The latter allows BatchRefine to take part in P3 pipelines where it can be chained with other transformers.

In either case, two things are needed to run BatchRefine:

  1. a CSV to use as input file;
  2. an OpenRefine command history (referred to as a transform script), packaged as a JSON file.

Try it out

To try BatchRefine right away, use the pre-built docker image

docker run --rm -it -p 8310:8310 fusepool/p3-batchrefine

This will start the P3 Batchrefine transformer with default configurations, which can be accessed as follows:

curl -XPOST -H 'Content-Type:text/csv' --data-binary @input.csv 'localhost:8310/?refinejson='

Compiling and Running

Building from Sources

Building BatchRefine from sources requires Maven 3 and Apache ant (for building OpenRefine). The procedure, which is somewhat complex because OpenRefine is not meant to be used as a library, is as follows. In a clean folder:

  1. Download the OpenRefine 2.6-beta.1 source distribution from:

  2. Unzip, untar, and then build OpenRefine, the server and web app JARs by running:

    ant build jar_server jar_webapp
  3. Switch to the ./extensions folder under the OpenRefine root and then download the OpenRefine RDF extension alpha 0.9.0 source distribution:

    Unzip, untar, and then rename the folder it extracts into rdf-extension and build it as follows:

    mv grefine-rdf-extension-0.9.0 rdf-extension
    cd rdf-extension
    JAVA_TOOL_OPTIONS='-Dfile.encoding=UTF-8' ant build
  4. After that, switch back to the OpenRefine root and start it (./refine). A running instance is required for the tests that BatchRefine will run during the build.

  5. Download BatchRefine from:

    into a sibling folder to OpenRefine (i.e. both OpenRefine and BatchRefine should share the same parent folder). As usual, unzip and untar. Switch to the p3-batchrefine-v1.x.x folder, and run:

    mvn package

The JAR for starting the P3 transformer will be located under:


whereas the JAR for starting the command line client will be under:



This section describes how to run the tools, for more details refer to Usage section.

Run the Command Line Tool

./bin/batchrefine [--verbose] BACKEND_TYPE [backend_specific_options] INPUTFILE TRANSFORM [OUTPUTFILE]

If no OUTPUTFILE is specified, writes to STDOUT

Available backends:
remote    - simple http client that connects to an OpenRefine instance
split     - distributed backend able to connect to multiple OpenRefine instances and improve
            performance by splitting input file.
embedded  - built-in OpenRefine allows to run transforms without starting
            an external OpenRefine instance (currently has limited functionality)
spark     - distributed backend based on Apache Spark aimed at very large workloads 
            (currently has limited functionality)

To list the backend_specific_options:

./bin/batchrefine BACKEND_TYPE --help

Run the P3 Transformer

./bin/transformer [TRANSFORMER_OPTIONS] BACKEND_TYPE [backend_specific_options]


-v                -- verbose logging
-p [PORT]         -- port to which transformer listens (defaults: 8310)
-t [sync|async]   -- transformer type: synchronous or asynchronous (defaults to sync)

Available backends for the transformer are: remote, split, spark

backend_specific_options are the same as for the command line client and can be listed with a --help option or, consult the Usage section

To start the most common configuration of the transformer (running synchronously on port 8310 and connecting to a locally running instance of OpenRefine):

./bin/transformer remote

#which is equivalent to:

./bin/transformer -v -t sync -p 8310 remote -l localhost:3333


This section provides usage examples for both Command Line Tool and P3 Transformer

Command Line Tool

Unfortunately, the command line tool has to be built from sources. Read the section on building BatchRefine from sources for instructions on how to do it.

The HTTP API is convenient for integrating BatchRefine as a service, but clumsy for manual usage. The command line tool works better in these cases, as you can simply do:

./bin/batchrefine remote input.csv transform.json > output.csv

where, as before, input.csv is the input file, transform.json is the transform script and output.csv is the output file to which to write the transformed data.

Running With the Embedded Backend

We ship a prepackaged script to start the command line tool under ./bin. We will show an example using the embedded backend so that you do not need to start OpenRefine to actually use it.

./bin/batchrefine embedded input.csv transform.json

this will produce a CSV file on stdout with the transform applied to it.

Limitations of the embedded engine

The embedded engine cannot currently do reconciliation, and extensions require customization to work (i.e. the RDF extension won't work out of the box). Further, it is likely that it has to be altered or rewritten to work with newer versions of OpenRefine.

If you get JSON exeptions like org.json.JSONException check the file size of your input JSON file. BatchRefine does not accept large input JSON files and you might have to shrink it to a few 100kB to get rid of it. This can be done by not selecting the whole history in OpenRefine, which can make the configuration really big (a few megabytes).

Accessing a running OpenRefine instance

The command line tool can also act as a direct client to a running OpenRefine instance. If you have OpenRefine running on, you can use the command line client as follows:

./bin/batchrefine remote -l input.csv transform.json

Simple distributed backend, accesing multiple OpenRefine instances

The command line tool can also split a large file for you and submit it to multiple OpenRefine instances. For example, you have two OpenRefine instances and you want to split your file in half:

./bin/batchrefine split -l, -s CHUNK:2 input.csv transform.json

the Batchrefine split backend will split an input file in 2 chunks, upload them to available OpenRefine instances and handle the reassembling of the result.

Command line options of split backend:

To get the list of available options, use --help option.

./bin/batchrefine split --help
 --help                              : Prints usage information
 -c (--config)     : Load batchrefine config from properties
 -f (--format) [csv | rdf | turtle]  : The format in which to output the
                                       transformed data
 -h (--hosts) localhost              : OpenRefine instances hosts
 -s (--split) [LINE:int | CHUNK:int] : Set default split logic
Split logic

Two split strategies are supported:

  • CHUNK:N - splits a file into N equal pieces
  • LINE:N1,N2,N3 - split the file on the specified line numbers, such that LINE:30,50,80 will split a file into 4 pieces on exectly specified lines.

P3 Transformer

The BatchRefine P3 transformer wraps (multiple instances of) OpenRefine under the Fusepool P3 HTTP API. We will show how to build a transformer that operates over a single instance, running locally.

Building with Docker

Building and deploying the P3 transformer with Docker is easy. Assuming you have Docker already installed, there are two main options, depending on your mileage:

  1. use the Dockerfile we provide;

  2. use our wrapper script. At the BatchRefine source root, run:

cd docker
./ bootstrap

After running the bootstrap step, you just have to run:

./ run

For more information regarding docker, refer to the docker README

and this will expose a synchronous BatchRefine P3 transformer on port 8310. To access the transformer, you have to make a POST request to it.

Docker image provides a running OpenRefine instance together with the transformer so you don't have to care about running your own.

Running with your OpenRefine instance

./bin/transformer -v -t sync remote -l

Will start a synchronous P3 Transformer which will connect to the specified OpenRefine instance. If no URI is specified, defaults to: localhost:3333.


As per the P3 transformer API, the input file goes in the body of the POST request, whereas the transform script goes as an URI passed as a query parameter called refinejson in our case. Assuming our input file is called input.csv and is available locally, and our transform script is called transform.json and is available at, we could do a request like:

curl -XPOST --data-binary @input.csv --H 'Content-Type:text/csv' -H 'Accept:text/csv'

to which the transformer will reply with a CSV file that has been transformed according to what is described in transform.json.

NB: Although transform scripts can be taken from local URIs such as file://tmp/transform.json, BatchRefine won't be able to access them when running inside Docker. If you want to post file URIs, it's best to build and run the transformer from sources (see the section on building BatchRefine from sources).


This work is partially funded by Fusepool P3 project, under FP7 grant 609696.