chore: readme

README.md

@@ -0,0 +1,33 @@
+[![Build Status](https://travis-ci.org/DD-DeCaF/id-mapper.svg?branch=master)]()
+[![Codecov](https://codecov.io/gh/DD-DeCaF/id-mapper/branch/master/graph/badge.svg)](https://codecov.io/gh/DD-DeCaF/id-mapper)
+
+# ID Mapper
+
+Powered by [Venom](https://github.com/biosustain/venom)
+
+Based on [MetaNetX](http://www.metanetx.org/). Information about metabolites and reactions is provided by [MNXref namespace](http://www.metanetx.org/mnxdoc/mnxref.html)
+
+Example on how to find a match for the chemical with [BIGG](https://github.com/biosustain/venom) id `nh3` in [BioPath](https://webapps.molecular-networks.com/biopath3/biopath3) database:
+
+```
+GET /idmapping/query?id=nh3&db_from=bigg&db_to=biopath HTTP/1.1
+Accept: */*
+Accept-Encoding: gzip, deflate
+Connection: keep-alive
+
+
+HTTP/1.1 200 OK
+Connection: keep-alive
+Content-Length: 36
+Content-Type: application/json
+
+{
+    "ids": [
+        "Ammonia",
+        "Ammonium-ion"
+    ]
+}
+```
+
+The graph consists of large amount of connected components. A connected component is considered being one object: a metabolite or a reaction. Search is returning all the elements in the component with `db_to` database name.
+![graph](graph.png)