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API Aggragation sample in microservices
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| /* | |
| * Parses the request and dispatches multiple concurrent requests to each | |
| * internal endpoint. Results are aggregated and returned. | |
| */ | |
| function serviceDispatch(req, res) { | |
| var parsedUrl = url.parse(req.url); | |
| /*Service is where we maintain the requests which we want to aggregate/ | |
| Service.findOne({ url: parsedUrl.pathname }, function(err, service) { | |
| if(err) { | |
| logger.error(err); | |
| send500(res); | |
| return; | |
| } | |
| var authorized = roleCheck(req.context.authPayload.jwt, service); | |
| if(!authorized) { | |
| send401(res); | |
| return; | |
| } | |
| // Fanout all requests to all related endpoints. | |
| // Results are aggregated (more complex strategies are possible). | |
| /*Calling out all requests and then aggregating them in one*/ | |
| var promises = []; | |
| service.endpoints.forEach(function(endpoint) { | |
| logger.debug(sprintf('Dispatching request from public endpoint ' + | |
| '%s to internal endpoint %s (%s)', | |
| req.url, endpoint.url, endpoint.type)); | |
| switch(endpoint.type) { | |
| case 'http-get': | |
| case 'http-post': | |
| promises.push(httpPromise(req, endpoint.url, | |
| endpoint.type === 'http-get')); | |
| break; | |
| case 'amqp': | |
| promises.push(amqpPromise(req, endpoint.url)); | |
| break; | |
| default: | |
| logger.error('Unknown endpoint type: ' + endpoint.type); | |
| } | |
| }); | |
| /*Maintaing that queue and then playing in queue*/ | |
| //Aggregation strategy for multiple endpoints. | |
| Q.allSettled(promises).then(function(results) { | |
| var responseData = {}; | |
| results.forEach(function(result) { | |
| if(result.state === 'fulfilled') { | |
| responseData = _.extend(responseData, result.value); | |
| } else { | |
| logger.error(result.reason.message); | |
| } | |
| }); | |
| res.setHeader('Content-Type', 'application/json'); | |
| res.end(JSON.stringify(responseData)); | |
| }); | |
| }, 'services'); | |
| } | |
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