Posts Tagged ‘nodejs’

Connecting to MQ Light from a web app via WebSockets

Monday, May 25th, 2015

How to subscribe to MQ Light notifications from a web app, via a WebSockets bridge

I’ve been working on a microservices app hosted on Bluemix. It’s one logical app, but it’s implemented and deployed as a bunch of separate Bluemix applications, each with it’s own separate responsibility.

I’m using MQ Light as asynchronous messaging between the apps. Each Bluemix app publishes notifications about changes to resources, and the status of long-running tasks.

mqlight on Bluemix

I won’t labour why or how we do this here, as it’s well covered in many other posts on microservices. For example:

…publish everything, however boring and insignificant it may seem to the rest of the system. Publishing is very lightweight and the publisher does not need to know whether 0 or 1000 other services are interested in that particular event, just fire and forget. This is extremely powerful and is what enables microservices to be built and deployed extremely quickly…

This is working well, but I also want a web app to be able to get some of these notifications.

If the web app has a resource open for editing, I want it to get a push notification if there are any changes to the resource.

If the web app started a long-running task, I want it to get push notifications of status changes.

I’ve done this by writing a small proxy, allowing a web app to subscribe to MQ Light topics and get the message via WebSockets.

Essentially, it’s an mqlight-WebSockets bridge.

mqlight with WebSockets on Bluemix


How to use the IBM Watson Relationship Extraction service on Bluemix

Sunday, January 25th, 2015

Before Christmas, I wrote about how I used the Watson Relationship Extraction service on Bluemix to pick out the things mentioned in news stories, as part of a mobile app we built on a hackday. I’d still like to do something more with that app, but in the meantime I should at least share how I did the Relationship Extraction bit.

From the official doc for the service:

From unstructured text, Relationship Extraction can extract entities (such as people, locations, organizations, events), and the relationships between these entities (such as person employed-by organization, person resides-in location).

This is provided as a hosted service on IBM Bluemix where any developer can sign up and give it a try.

It’s available as a documented REST API, but as part of using it in the hackday, I needed to write a bit of code around that, just to prepare the request and parse the response. I think it’ll save me time to reuse this the next time I want to build something with the API, so I’m sharing it as a standalone package.

In this post, I’ll walk though how you can use it, with a small app that grabs the contents of a BBC News story and picks out the names of people mentioned in the story.


Using Node.js to create a REST API around a SQL database

Sunday, June 15th, 2014

A few code snippets for how you can quickly stand up a SQL database, and provide a REST API for DB read/writes

I was helping out a team at a hackday hosted at Hursley last week. One of the things they wanted for their hack was a SQL database to put sensor data in, which they could access via a REST API. And they wanted it in node.js.

I’d never used Node before, so I used this as a chance to give myself a first crash-course.

I’m not saying this is the way to do this in Node, as it’s the result of my first hour’s tinkering. But it worked, and I mostly wanted to share how quick and easy it was.