Stetl 1.1

# Stetl - Streaming ETL

Stetl, streaming ETL, pronounced "staedl", is a lightweight ETL-framework for geospatial data conversion.

[](https://travis-ci.org/geopython/stetl)
[](http://stetl.readthedocs.org/en/latest)
[](https://gitter.im/justb4/stetl)

Notice: the Stetl GH repo is now at the [GeoPython GH organization](https://github.com/geopython).

# License

Stetl is released under a [GNU GPL v3](https://en.wikipedia.org/wiki/GNU_General_Public_License) license
(see [LICENSE.txt](LICENSE.txt)).

## Documentation

The Stetl website and documentation can be found via http://stetl.org.
For a quick overview read the [5-minute Stetl-introduction](http://www.slideshare.net/justb4/5-minute-intro-to-setl),
or a [more detailed presentation](http://www.slideshare.net/justb4/stetl-foss4g20131024v1).
Stetl was presented at several events like the
[FOSS4G 2013 in Nottingham](http://2013.foss4g.org) and [GeoPython 2016](http://www.geopython.net).

## Concepts

Stetl basically glues together existing parsing and transformation tools like [GDAL/OGR](http://gdal.org), Jinja2 and
XSLT with custom Python code. By using native libraries like `libxml2` and `libxslt` (via Python `lxml`) Stetl is speed-optimized.

A configuration file, in Python config `.ini` format, specifies a chained sequence of transformation
steps: typically an `Input` connected to one or more `Filters`, and finally to an `Output`.
At runtime, this sequence is instantiated and run as a linked series of Python objects. These objects are
symbolically specified (by their module/class name) and parameterized in the config file.
Via the `stetl -c <config file>` command, the transformation is executed.

Stetl has been proven to handle 10's of millions of GML objects without any memory issues.
This is achieved through a technique called "streaming and splitting".
For example: using the `OgrPostgisInput` module an GML stream can be generated from the database.
A component called the `GmlSplitter` can split this stream into manageable chunks (like 20000 features)
and feed this upstream into the ETL chain.

## Use Cases

Stetl has been found particularly useful for complex GML-related ETL-cases, like those found
within [EU INSPIRE](http://inspire.ec.europa.eu/) Data Harmonization and the transformation
of GML/XML-based National geo-datasets to for example PostGIS.

Most of the data conversions within the [Dutch NLExtract Project](https://github.com/nlextract/NLExtract) apply Stetl.

Stetl also proved to be very effective in [IoT-related transformations involving the SensorWeb/SOS](https://github.com/Geonovum/smartemission).

## Examples

Browse all examples under the [examples dir](examples).
Best is to start with the [basic examples](examples/basics)

## Installation

Stetl can be installed via PyPi `pip install stetl` and recently as a [Stetl Docker image](https://hub.docker.com/r/justb4/stetl).
More on [installation in the documentation](http://www.stetl.org/en/latest/install.html).

## Contributing

Anyone and everyone is welcome to contribute. Please take a moment to
review the [guidelines for contributing](CONTRIBUTING.md).

* [Bug reports](CONTRIBUTING.md#bugs)
* [Feature requests](CONTRIBUTING.md#features)
* [Pull requests](CONTRIBUTING.md#pull-requests)

## Origins

Stetl originated in the INSPIRE-FOSS project: [2009-2013 now archived](https://github.com/justb4/inspire-foss).
Since then Stetl evolved into a wider use like
transforming [Dutch GML-based Open Datasets](https://github.com/nlextract/NLExtract) such as IMGEO/BGT (Large Scale Topography)
and IMKAD/BRK (Cadastral Data).

## Finally

The word "stetl" is also an alternative writing for "shtetl":
http://en.wikipedia.org/wiki/Stetl : "...Material things were neither disdained nor
extremely praised in the shtetl. Learning and education were the ultimate measures of
worth in the eyes of the community,
while money was secondary to status..."




Changes
=======

v1.1.1 - november 7, 2017
-------------------------

Biggest change is that the Stetl repo moved to https://github.com/geopython/stetl/.

See closed issues in Milestone 1.1.1: https://github.com/geopython/stetl/milestone/6?closed=1

Highlights:

- new Component Splitter to split (Filter/Output) data streams within a Chain
- new Component Merger to combine (Input) data streams within a Chain
- Splitter and Merger can be combined in single Chain
- automatic Travis build
- more Unit tests
- flake8 for clean Python code
- move to GDAL v2 (though v1 may still work)
- new compact Docker Image based on debian:stretch-slim
- bugfixes XML stream support

v1.0.9 - 17 june 2016
---------------------

See https://github.com/geopython/stetl/issues?q=milestone%3A%22Version+1.0.9%22+is%3Aclosed

Highlights:

- Substitutable config options in properties file (-a arg)
- Docker support via Stetl Docker image
- Generic ogr2ogr Input Component enhancement

v1.0.8 - 2 july 2015
--------------------

See https://github.com/geopython/stetl/issues?q=milestone%3A%22Version+1.0.8%22

- generic OgrOutput component
- Apache Log File Input

v1.0.7 - 24 nov 2014
--------------------

- start of Stetl Format conversion Filter
- generic OgrInput component
- SQLite Input component
- BAG to INSPIRE Addresses example with Jinja2 Templating Filter
- Jinja2 Filter refinements

v1.0.6 - 5 sept 2014
--------------------

- allow spatial_extent in OGROutput Top10NL example
- httpinput more robust
- Packet: new type 'record', as Python dict structure
- httpinput: ApacheDirInput, input data from Apache index listing
- dboutput: PostgresInsertOutput, insert single record into Postgres
- component: add before_/after_invoke and after_chain_invoke() for intercepting
- filters: start of Python Templating filters: simple string and Jinja2 templating
- Packet: new type 'struct' basically a free form dict, the result of reading CSV
- input: CSV file input
- new examples: 9_string_templating and 10_jinja2_templating
- start stetl --doc option to print class configuration info
- config: start of adding meta attribute config info via class vars of type Attr

v1.0.5 - 19 feb 2014
--------------------

- cater for strange lxml parse error: https://bugs.launchpad.net/lxml/+bug/1185701
- more Dutch BGT (large scale topo) examples by thijsbrentjens

v1.0.4 - 23 sept 2013
---------------------

- more documention
- Dutch BGT (Basis Registratie Grootschalige Topografie) example
- Ordnance Survey Mastermap example
- strip XML namespaces option to XmlElementStreamerFileInput

v1.0.1 v1.0.3 - aug/sept 2013
-----------------------------
Minor changes to enable distribution.


v1.0.0 - june 2013
------------------

- First version
- Add to Python Package Index (#3).

Credits
=======

Stetl is developed by:

* Just van den Broecke (initiator, http://www.justobjects.nl)
* Frank Steggink
* Thijs Brentjens
* and more, see contributors: https://github.com/geopython/stetl/graphs/contributors

Bas Couwenberg is providing Debian/Ubuntu packaging.

This project would not be possible without the great work of Frank Warmerdam and other
GDAL/OGR developers (http://gdal.org).

Plus the people that brought Python, PostGIS (Paul Ramsey et al.), Jinja2, lxml and the libs
like GEOS, Proj, libxml2 and libxslt.

We are mainly standing on the shoulders of these giants.

Thanks to Tom Kralidis for helping out to move from personal repo to https://github.com/geopython organization.