Quickstart

This quick tutorial shows how to start the swh.graph service to query an existing compressed graph with the high-level HTTP API.

Dependencies

In order to run the swh.graph tool, you will need Python (>= 3.7) and Java JRE. On a Debian system:

$ sudo apt install python3 python3-venv default-jre

Installing swh.graph

Create a virtualenv and activate it:

$ python3 -m venv .venv
$ source .venv/bin/activate

Install the swh.graph python package:

(venv) $ pip install swh.graph
[...]
(venv) $ swh graph --help
Usage: swh graph [OPTIONS] COMMAND [ARGS]...

  Software Heritage graph tools.

Options:
  -C, --config-file FILE  YAML configuration file
  -h, --help              Show this message and exit.

Commands:
  compress    Compress a graph using WebGraph Input: a pair of files...
  rpc-serve   run the graph RPC service

Retrieving a compressed graph

Software Heritage provides a list of off-the-shelf datasets that can be used for various research or prototyping purposes. Most of them are available in compressed representation, i.e., in a format suitable to be loaded and queried by the swh-graph library.

All the publicly available datasets are documented on this page: https://docs.softwareheritage.org/devel/swh-dataset/graph/dataset.html

A good way of retrieving these datasets is to use the AWS S3 CLI.

Here is an example with the dataset 2021-03-23-popular-3k-python, which has a relatively reasonable size (~15 GiB including property data, with the compressed graph itself being less than 700 MiB):

(venv) $ pip install awscli
[...]
(venv) $ mkdir -p 2021-03-23-popular-3k-python/compressed
(venv) $ cd 2021-03-23-popular-3k-python/
(venv) $ aws s3 cp --recursive s3://softwareheritage/graph/2021-03-23-popular-3k-python/compressed/ compressed

You can also retrieve larger graphs, but note that these graphs are generally intended to be loaded fully in RAM, and do not fit on ordinary desktop machines. The server we use in production to run the graph service has more than 700 GiB of RAM. These memory considerations are discussed in more details in Memory & Performance tuning.

Note: for testing purposes, a fake test dataset is available in the swh-graph repository, with just a few dozen nodes. Its basename is swh-graph/swh/graph/tests/dataset/compressed/example.

API server

To start a swh.graph API server of a compressed graph dataset, you need to use the rpc-serve command with the basename of the graph, which is the path prefix of all the graph files (e.g., with the basename compressed/graph, it will attempt to load the files located at compressed/graph.{graph,properties,offsets,...}.

In our example:

(venv) $ swh graph rpc-serve -g compressed/graph
Loading graph compressed/graph ...
Graph loaded.
======== Running on http://0.0.0.0:5009 ========
(Press CTRL+C to quit)

From there you can use this endpoint to query the compressed graph, for example with httpie (sudo apt install httpie):

~/tmp$ http :5009/graph/leaves/swh:1:dir:432d1b21c1256f7408a07c577b6974bbdbcc1323
HTTP/1.1 200 OK
Content-Type: text/plain
Date: Tue, 15 Sep 2020 08:35:19 GMT
Server: Python/3.8 aiohttp/3.6.2
Transfer-Encoding: chunked

swh:1:cnt:33af56e02dd970873d8058154bf016ec73b35dfb
swh:1:cnt:b03b4ffd7189ae5457d8e1c2ee0490b1938fd79f
swh:1:cnt:74d127c2186f7f0e8b14a27249247085c49d548a
swh:1:cnt:c0139aa8e79b338e865a438326629fa22fa8f472
[...]
swh:1:cnt:a6b60e797063fef707bbaa4f90cfb4a2cbbddd4a
swh:1:cnt:cc0a1deca559c1dd2240c08156d31cde1d8ed406

See the documentation of the API for more details on how to use the HTTP graph querying API.