datacache-client

datacache-client

NodeJS request-promise based client for IBM Bluemix Data Cache service.

Setup

npm install datacache-client

Using the Data Cache client in a Node JS application:

var DataCacheClient = require('datacache-client');
var dcClient = new DataCacheClient();

// save data to storage
dcClient.put('key-name', {item: 'test'})
	.then(function(resp) {
    	// data saved - continue your logic
        console.log('Data saved to storage at key "key-name"');
	}).catch(function(err) {
    	// something went wrong
        console.log('Failed to save data to storage');
    });

// get data from storage
dcClient.get('key-name')
	.then(function(resp) {
    	// data loaded in resp.body
        var obj = resp.body;
        console.log('Object returned with item ' + obj.item);
	}).catch(function(err) {
    	// no data found
        console.log('Failed to retrieve data from storage');
    });
    
// destroy data
dcClient.destroy('key-name')
	.then(function(resp) {
    	// data deleted from storage
        console.log('Data deleted for "key-name"');
	}).catch(function(err) {
    	// no data found
        console.log('Failed to delete data from storage');
    });

API

.put(key, data, ttl)

key - string - name of the key to put data under in DataCache

data - Object|string - Data to be saved to cache service - based on the contentType parameter for the client it saves it as JSON or plain text

ttl - optional - overrides the client Time To Live default value (seconds)

returns: Promise

.get(key)

key - string - key name to be used for retrieval of data from cache storage

returns: Promise - resolved value has the full response (check resolveWithFullResponse parameter for request-promise)

ex: resolved.body - Object retrieved from cache resolved.statusCode - Status code from REST API

.destroy(key)

key - string - key name to be used for deletion

returns: Promise - resolved value has the full response (check resolveWithFullResponse parameter for request-promise)

Storage Options

Bellow is an example with the full list of parameters - default values for optional ones:

var store = new DataCacheClient({
        // required parameters when no custom client provided
        restResource: 'http://dcsdomain.bluemix.net/resources/datacaches/{gridName}',
        restResourceSecure: 'https://dcsdomain.bluemix.net/resources/datacaches/{gridName}',
        gridName: '{gridName}',
        username: '{username}',
        password: '{password}',
        // optional parameters - default values
        mapName: '{gridName}',
        eviction: 'LUT',
        locking: 'optimistic',
        contentType: 'application/json',
        secure: true,
        ttl: 3600,
        cfenvServiceName: null
    }
);

Bluemix environment

The datacache client is looking first for DataCache service cfenv values. For the Bluemix NodeJS app with a DataCache service associated the required parameters are read from ENV variables (credentials):

Environment Variables > VCAP_SERVICES

{
    "system_env_json": {
      "VCAP_SERVICES": {
         "DataCache-dedicated": [
            {
               "credentials": {
                 "catalogEndPoint": "...",
                 "restResource": "http://ip-numeric/resources/datacaches/SYS_GENERATED_GRIDNAME",
                 "restResourceSecure": "https://sdomain.bluemix.net/resources/datacaches/SYS_GENERATED_GRIDNAME",
                 "gridName": "SYS_GENERATED_GRIDNAME",
                 "username": "sysGeneratedUsername",
                 "password": "sysGeneratedPass"
               },
               "name": "datacache-service-name",
               "tags": []
            }
         ]
      }
   },
}

restResources/restResourceSecure

defaults: VCAP_SERVICES credentials values

Depending on the "secure" value, one of them is required if not found in ENV variables by cfenv.

mapName

For a Bluemix application it is required to have the same value as for "gridName". A resource is identified with a complete URI as:

http://secure.domain/resources/datacaches/SYS_GENERATED_GRIDNAME/MAP_NAME.EVICTION.LOCK/SESSION_KEY

ex: https://ecaas3.w3ibm.bluemix.net/resources/datacaches/Ae7hjz7tQjuxF44ncLAvuQGH/Ae7hjz7tQjuxF44ncLAvuQGH.LUT.O/sess:t7OQGXZ3x8TNp269-lf-wsdnUBx5OcU6

For non-Bluemix environments can be customized as a namespace for data.

eviction

• 'LUT' - default - expires based on the Last Update Time
• 'NONE' - data is stored indefinitly (until si programaticaly deleted)
• 'LAT' - expires based on Last Access Time

locking

• 'optimistic' - default
• 'pessimistic'

contentType

• 'application/json' - default - turns on the JSON encoder/decoder for stored data
• other - saves data as plain text

secure

• true - default - uses 'restResourceSecure' as store entrypoint
• false - uses 'restResource' as store entrypoint

ttl

• default storage time to live per client (seconds)

cfenvServiceName

• allows using multiple Data Cache services for same application - loads credentials from ENV using service name;

var dcClient = new DataCacheClient({'cfenvServiceName': 'datacache-service-name'});

Contributing

PR code needs to pass the lint check and unit test

npm test

PR code should be covered by UT

npm run coverage

Debugging

The module uses debug npm module - in order to turn the debuging on follow the steps:

Local environment:

$> DEBUG=datacache-client npm start

CF environmment (Bluemix) - using manifest.yml

applications:
- path: .
# ...
  env:
    DEBUG: datacache-client
  services:
  - datacache-service-name

Resources

• http://www.ibm.com/support/knowledgecenter/SSTVLU_8.6.0/com.ibm.websphere.extremescale.doc/tdevrest.html
• https://console.ng.bluemix.net/docs/services/DataCache/index.html#datac001
• https://github.com/request/request-promise