This guide will walk you through the core features of AntidoteDB. We will use Docker to run AntidoteDB nodes. Please refer to the complete installation guide if you wish to build the nodes from source.

In this guide, you will accomplish the following steps:

  • Start two AntidoteDB nodes and connect them to each other;
  • Start and commit a transaction;
  • Use the Bounded Counter data type.

Requirements

Create a cluster

If you prefer to skip the steps to build the cluster manually, there is a Docker Compose file available at: https://github.com/mweberUKL/antidote_dev/tree/master/docker_dcs.

Fetch AntidoteDB docker image by typing:

docker pull antidotedb/antidote

Create a virtual network interface:

docker network create --driver bridge default_ntwk

Start two AntidoteDB node instances which will be called ‘antidote1’ and ‘antidote2’:

docker run -i -t -d --name antidote1 --network default_ntwk -e SHORT_NAME=true -e NODE_NAME=antidote@antidote1 antidotedb/antidote

docker run -i -t -d --name antidote2 --network default_ntwk -e SHORT_NAME=true -e NODE_NAME=antidote@antidote2 antidotedb/antidote

Connect to the console of one node:

docker exec -it antidote1 /opt/antidote/bin/env attach

Run the following lines of code to connect the two nodes:

rpc:call(antidote@antidote1, inter_dc_manager, start_bg_processes, [stable]),
rpc:call(antidote@antidote2, inter_dc_manager, start_bg_processes, [stable]),
{ok, Desc1} = rpc:call(antidote@antidote1, inter_dc_manager, get_descriptor, []),
{ok, Desc2} = rpc:call(antidote@antidote2, inter_dc_manager, get_descriptor, []),
Descriptors = [Desc1, Desc2],
rpc:call(antidote@antidote1, inter_dc_manager, observe_dcs_sync, [Descriptors]),
rpc:call(antidote@antidote2, inter_dc_manager, observe_dcs_sync, [Descriptors]).

We now have an AntidoteDB cluster with two replicas!

Connecting to AntidoteDB

In two separate terminals, connect to the console of each node:

docker exec -it antidote1 /opt/antidote/bin/env attach

docker exec -it antidote2 /opt/antidote/bin/env attach

If you used the Compose file before, you connect to the console of a replica by typing: docker-compose exec antidote1 /opt/antidote/bin/env attach

Interacting with AntidoteDB

Start a new transaction and increment the value of a bounded counter. By default, if the counter does not exist, one is created automatically.

{ok, TxId} = antidote:start_transaction(ignore, []).
antidote:update_objects([{ {counter_key, antidote_crdt_bcounter, test_bucket}, increment, {10, client1}}], TxId).
antidote:commit_transaction(TxId).
# output: {ok, ...}

The counter can be decremented in the replica where it was created:

{ok, TxId1} = antidote:start_transaction(ignore, []).
antidote:update_objects([{ {counter_key, antidote_crdt_bcounter, test_bucket}, decrement, {1, client1}}], TxId1).
antidote:commit_transaction(TxId1).
# output: {ok, ...}

And the value of the counter can be read on the other replica (use the other terminal):

{ok, TxId} = antidote:start_transaction(ignore, []).
{ok, [Obj]} = antidote:read_objects([{counter_key, antidote_crdt_bcounter, test_bucket}], TxId).
antidote_crdt_bcounter:permissions(Obj).
# output: 9

But cannot be decremented:

{error, _} = antidote:update_objects([{ {counter_key, antidote_crdt_bcounter, test_bucket}, decrement, {1, client2}}], TxId).
# output: {error,{aborted, ...}}

At this point, the transaction aborts and the system will automatically fetch permissions from another replica. After the resources are transfered between nodes, it is possible to decrement the counter.

{ok, TxId1} = antidote:start_transaction(ignore, []).
antidote:update_objects([{ {counter_key, antidote_crdt_bcounter, test_bucket}, decrement, {1, client2}}], TxId1).
antidote:commit_transaction(TxId1).
# output: {ok, ...}

Look at the documentation to see more examples of AntidoteDB in action. We are working on new features for AntidoteDB, contact us at info@antidotedb.com if you want to know more.

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