Mongo-Emitter

MongoDB

We use a MongoDB database to store the data collected from running simulations via the DatabaseEmitter class. The use of this class is specified in the 'emitter' section of the instance declaration for a given process as such:

...,
'emitter': {
                '_type': 'step',
                'address': 'local:database-emitter',
                'config': {
                    'ports': {
                        'inputs': {
                            'table': 'string',

. This can be a remote server, but for this guide we will run a MongoDB server locally.

Note: MongoDB is only required if you want to store data in MongoDB or want to run experiments that do so via the declaration shown above. You don't need MongoDB to work through this guide.

Check Installation

$ mongod --version
db version v4.2.3
...

Make sure you see a version at least 3.2.

Install

If you are on macOS, you can install MongoDB using Homebrew. You will need to add the MongoDB tap following the instructions here.

If you are on Linux, see the MongoDB documentation's instructions.

Setup

You can get a MongoDB server up and running locally any number of ways. Here is one:

1. Create a folder process_bigraph_work/mongodb. This is where MongoDB will store the database We store the database here instead of at the default location in /usr/local/var/mongodb to avoid permissions issues if you are not running as an administrator.

2. Make a copy of the mongod configuration file so we can make changes:

   $ cp /usr/local/etc/mongod.conf process_bigraph_work/mongod.conf
   

   Note that your configuration file may be somewhere slightly different. Check the MongoDB documentation for your system.

3. In process_bigraph_work/mongod.conf change the path after dbPath: to point to process_bigraph_work/mongodb.

4. Create a shell script process_bigraph_work/mongo.sh with the following content:

   #!/bin/bash
   
   mongod --config mongod.conf
   

5. Make the script executable:

    $ chmod 700 process_bigraph_work/mongo.sh
   

6. Now you can launch MongoDB by running this script:

    $ process_bigraph_work/mongo.sh