#Erldyn

##DynamoDB API DynamoDB functions are converted to underscore_case functions of arity 1:<br/>

• batch_get_item/1,
• batch_write_item/1,
• create_table/1,
• delete_item/1,
• delete_table/1,
• describe_table/1,
• get_item/1,
• list_tables/1,
• put_item/1,
• query/1,
• scan/1,
• update_item/1,
• update_table/1]

The single parameter is JSON as defined by the DynamoDB API, and the returns are either: <br/>

• {ok, #{...}},
• [{ok, #{...}}, ...],
• or {error, #{...})

where the maps are map versions of DynamoDB, JSON returns.

###Batch Functions The batch functions (batch_get_item/1 and batch_write_item/1) can return partial results. The unprocessed items will be resubmitted automatically, consequently, these functions return a list of maps - one for each partial result.

##Convenience Methods Convenience methods (new_table/3, save_table/1, and add_parameter/3) are provided for simplifying the process of building the correct strcture for defining and creating tables.

##Exponential Back-Off Exponentional back-off is used such that appropriate failures, or partial results, are retried according to an exponential, back-off algorithm, not to exceed one minute total for the entire operation.

##Authorization All http operations are PUTS, and Version 4 of the Signature authorizaion header is used.

Secret Key and Access Keys can be fetched form OS environment variables (AWS_ACCESS_KEY_ID, and AWS_SECRET_ACCESS_KEY) or set/changed via config/1.

If AWS Security Token Service is being used then the Token can only be supplied via the config map.

The DynamoDB Endpoint is provided via the same config/1 function, and is parsed to determine service, streaming service, host and region.

=> ConfigMap = #{endpoint => "https://dynamodb.us-west-2.amazonaws.com/",
              access_key => "AKIAIX5A77AFFFW7JLA",
              secret_key => "WIcKN27iNhkvsaEtGgPd9iqBFFFhEkas0rsDzoSA",
              token => "XXXXXXXXXXXXXXXXXX"}.
=> erldyn:config(ConfigMap).
=> ok

PROCESS DICTIONARY IS USED: <br/>

• put(access_key, ...) <br/>
• put(secret_key, ..) <br/>
• put(token, ..) <br/>
• put(stream_endpoint, ...) <br/>
• put(endpoint, ...) <br/>
• put(host, ...) <br/>
• put(service, ..) <br/>
• put(region, ..) <br/>

Dependencies

Lager for logging, jsone for json <--> map translation, and rebar3 for building

Build

erldyn uses rebar3

$ make compile
$ make clean
$ make doc
$ make check
$ make run

Running

Assuming that $ make has been previously executed:

$ export AWS_SECRET_ACCESS_KEY="WIcKN27efefff499Pd9iqBpm3hEkas0rsDzoSA"
$ export AWS_ACCESS_KEY_ID="AKERTJFFIFATLGIJFJLA"

$ make run
erl -pa _build/default/lib/*/ebin
Erlang/OTP 18 [erts-7.1] [source-2882b0c] [64-bit] [smp:8:8] [async-threads:10] [hipe] [kernel-poll:false]

Eshell V7.1  (abort with ^G)

1> erldyn:config(#{endpoint => "https://dynamodb.us-west-2.amazonaws.com/"}).
ok
2> erldyn:list_tables("{}").
{ok,#{<<"TableNames">> => [<<"Forum">>,<<"Reply">>,<<"Thread">>,<<"Wizzards">>]}}