Amp-Node Client

Amp-Node Client Overview

The Amp-Node Client library has an Amp class. It can be used to construct an Amp instance used to represent a single Amp project and needs to be initialized with a project key and a list of domain, which is the URL of the Amp Agent.

Note: Contact support@scaledinference.com for more information on integrating with our Amp-Agent. Amp-Agent is required to run the Amp-Node client.

Installing Amp-Node Client

npmi--saveamp-node

The single Amp instance can then be used to create multiple session objects which has three methods: decideWithContext, decide and observe.

Amp()

After importing amp-node, the Amp constructor can be used to create an Amp instance. It requires two parameters: a project key and the Amp-agent URL (with port 8100) where as timeOutMilliseconds default to 10 seconds, sessionLifetimeInSeconds default to 30 minutes.

Importing and Initializing Amp

constAmp=require("amp-node");
...
constamp=newAmp("YOUR_PROJECT_KEY",["List of AMP_AGENT_URL"],timeoutInMilliseconds,sessionLifetimeInSeconds,dontUseTokens);

amp.Session()

The session constructor is used to create a session (object):

Initializing the Session

constsession=newamp.Session();

Session objects created by an Amp instance support three methods: decideWithContext, decide and observe.

session.decideWithContext()

The decideWithContext method is synchronous and used to make decision for the provided context and properties. This method takes five arguments: name of the context event name, a property object of names to values for the context, name of the decision event, a list of variations to choose from and an override to the default timeout which needs to non-zero value in order to take effect.

/** * Decision to determine action for the provided context name and properties * * @param {string} contextName - name of the context event name * @param {object} context - properties to observe * @param {string} decisionName - name of the event * @param {object} candidates - variations to choose from * @param {int} timeout - request timeout in milliseconds will override the value from session or amp. Needs to be non-zero value in order to take effect.  * * @example * const context = { browser_height: 1740, browser_width : 360 }; * const candidates = {color:['red', 'green', 'blue'], count:[10, 100]}; * * session.decideWithContext( * 'AmpSession', context, * 'NodeDecisionWithContext', candidates, 3000 * ); * */Promise<decideResponse>decideWithContext(contextName,context={},decisionName,candidates,timeout)

session.observe()

The observe method is used to send observations.

/** * observe, send observation with event name and properties related to  * observation  * * @param {string} contextName - name of the context * @param {object} context - properties to observe * @param {int} timeout - request timeout in milliseconds will override the value from session or amp * @return {Promise<observeResponse>} * * @example *  * session.observe('NodeObserveMetric',context); *  */Promise<observeResponse>observe(contextName,context,timeout)

Example Usage

node ./examples/example.js <project_key> http://localhost:8100

console.log(`This will demonstrate how to use the node thin client to communicate with amp agent. Make sure you pass in a valid project key and your domain to your amp agent, if you use a different apiPath, make sure you pass that too.`);// import the Amp libraryconstAmp=require("../Amp");// parse the arguments from command line// node example.js <key> <domain> <apiPath>constprojectKey=process.argv[2];constampAgents=process.argv.slice(3);// create an amp instance with the key, domain, apiPathconstamp=newAmp(projectKey,ampAgents);console.log(`amp instance initialized`);// create a session instance// can also specify the `userId`, `timeout` here: {userId: "guestUser"}constsession=newamp.Session();console.log(`session instance initliazed`);// send decideWithContextconstcontext={browser_height: 1740,browser_width : 360};constcandidates={color:['red','green','blue'],count:[10,100]};constresponse=awaitsession.decideWithContext('AmpSession',context,'NodeDecisionWithContext',candidates,3000);if(response.fallback){console.log('Decision NOT successfully obtained from amp-agent. Using a fallback instead.');console.log(`The reason is: ${response.failureReason}`);}else{console.log('Decision successfully obtained from amp-agent');}// send observeconstobserveResponse=awaitsession.observe('NodeObserveMetric',context);if(!observeResponse.success){console.log('Observe NOT successfully sent to amp-agent.');// eslint-disable-line no-consoleconsole.log(`The reason is: ${observeResponse.failureReason}`);// eslint-disable-line no-console}else{console.log('Observe successfully sent to amp-agent.');// eslint-disable-line no-console}