Archive for the ‘code’ Category

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Has today been a good day?

Monday, April 16th, 2012

Last week, I came up with a quick hack, explained quite neatly by @crouchingbadger:

It was a bit of fun, even if it did seem to convince a group of commenters on engadget that I was a rage-fuelled XBox gamer. 🙂

There’s one big limitation with the hack, though: I don’t spend that much of my day in front of the TV.

It’s interesting to use it to measure my reactions to specific TV programmes or games. But thinking bigger, it’d be cool to try a hack that monitors me throughout the day to measure what kind of day I’m having.

I don’t spend much time in front of the TV, but I do spend a *lot* of time in front of my Macbook. And it has a camera, too!

What if my MacBook could look out for my face, and whenever it can see it, monitor what facial expression I have and whether I’m smiling? And while I’m at it, as I’ve been playing with sentiment analysis recently, add in whether the tweets I post sound positive or neutral.

Add that together, and could I make a reasonable automated estimate as to whether I’m having a good day?

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Posted in code | 3 Comments »

Smile!

Tuesday, April 3rd, 2012

The visualisations on this page need Flash and Javascript. Apologies if that means most of this page doesn’t work for you!

This is my mood (as identified from my facial expressions) over time while watching Never Mind the Buzzcocks.

The green areas are times where I looked happy.

This shows my mood while playing XBox Live. Badly.

The red areas are times where I looked cross.

I smile more while watching comedies than when getting shot in the head. Shocker, eh?

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Posted in code | 21 Comments »

Avoiding my Lucene TooManyClauses exceptions

Tuesday, March 20th, 2012

Before I start, I should point out that I’m not a Lucene expert. This post isn’t a definitive “you should do things this way” commandment from a Lucene mage. Think of it more as “I had this problem, and this seemed to work for me. I’m sharing it in case it helps you, too”.

I’m using Lucene to implement searches. Recently, as my Lucene index has grown (a lot), I was getting a lot of these errors when I tried to do a search:

org.apache.lucene.search.BooleanQuery$TooManyClauses: maxClauseCount is set to 1024
    at org.apache.lucene.search.BooleanQuery.add(BooleanQuery.java:163)
    at org.apache.lucene.search.BooleanQuery.add(BooleanQuery.java:154)
    at org.apache.lucene.search.MultiTermQuery.rewrite(MultiTermQuery.java:63)
    at org.apache.lucene.search.WildcardQuery.rewrite(WildcardQuery.java:54)
    at org.apache.lucene.search.BooleanQuery.rewrite(BooleanQuery.java:383)
    at org.apache.lucene.search.BooleanQuery.rewrite(BooleanQuery.java:383)
    at org.apache.lucene.search.IndexSearcher.rewrite(IndexSearcher.java:162)
    at org.apache.lucene.search.Query.weight(Query.java:94)
    at org.apache.lucene.search.Searcher.createWeight(Searcher.java:185)
    at org.apache.lucene.search.Searcher.search(Searcher.java:86)

I’m guessing that TooManyClauses is a common problem for people getting going with Lucene.

It’s mentioned in the FAQ, and there are a few StackOverflow threads around about it.

But I couldn’t find a straightforward “you need to follow these steps to fix it” post anywhere, so I’ll add my experience here.

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Posted in code | Comments Closed

Migrating from ActiveMQ to WebSphere MQ

Tuesday, March 13th, 2012

Overview

A side-project I’ve been playing with in the evening: Writing a JMX layer to allow apps written for ActiveMQ to migrate to WebSphere MQ with minimal modifications

Background

This came out of working on something that uses a JMS messaging provider. It uses it internally to allow components to communicate with each other, even when spread across multiple machines.

It uses Apache ActiveMQ – an open-sourced implementation of JMS. I wanted to try and get it working using WebSphere MQ – IBM’s implementation of JMS that I used to work on until five years ago.

As a messaging standard, the fact that both ActiveMQ and WebSphere MQ (WMQ) are JMS providers means that the way it puts and gets messages should just work.

But the JMS standard doesn’t cover administration (how queue managers are created and configured, how they’re started, how queues and topics are created, etc.) or monitoring (getting statistics about how many messages have been put or got, how many messages are on a queue, etc.)

All of this was done in an ActiveMQ-specific ways. This was what needed to be ported if I was going to get this to work with WebSphere MQ.

The project I’m porting is actually a bit of a black box. Rather than make a significant rewrite to get it to go from being ActiveMQ-specific to WMQ-specific, I wanted to see what I could add so that as much of the existing code could just work transparently.

I wanted to write a layer to sit between the ActiveMQ-app and WebSphere MQ, so that the app needn’t realise it’s not talking to the ActiveMQ broker it was written for.

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Posted in code, ibm | 4 Comments »

ETag header missing in HTTP No Content responses in Internet Explorer

Sunday, February 26th, 2012

If you’re one of that exceedingly rare breed who regularly check or subscribe to my blog, you probably want to give this post a miss. This one is more for people who find me through Google. A specific solution to a specific, geeky, problem.

Background

First a little scene setting…

Server side

I have a REST API that uses ETags for, amongst other things, concurrency control. That is, the version of an entity is (opaquely) identified by an ETag. You need to specify that ETag when you try and make any changes to that entity. If someone else changes the entity before you do, your ETag won’t match, so your update will fail, and you won’t unintentionally roll-back their change.

The REST API returns no content (HTTP 204) in response to a successful PUT request to edit an entity, and includes the new ETag representing the version of the updated entity.

Client side

I have a Dojo web tool that uses xhr.put to submit edits to the REST API. In order to make further subsequent edits to an entity without reloading the page, it stores the ETag that it gets back in the response header after every PUT.

The problem

In short, Internet Explorer. 🙂

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Posted in code | 2 Comments »

Posting to IBM Connections from WP7

Friday, February 24th, 2012

IBM Connections is something we use at work: an internal, intranet-hosted social network for work stuff.

I use stuff like the wikis, file sharing, and bookmarks, quite a lot. But I don’t make status updates as often as I could.

I wonder if that’s because I couldn’t do it from my phone? I know that I certainly started using Facebook a lot more since getting a phone with support for posting to facebook and twitter built-in.

So I set up a way for me to post to Connections from my phone with just one tap on the home screen.

Well, one tap, plus all the taps to actually type the status message… plus another tap on the Send button. But you get the idea.

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Posted in code, ibm | 1 Comment »

Generating a list of REST APIs in JAX-RS

Saturday, January 14th, 2012

Overview

Using Java Reflection to generate a list of REST endpoints defined in JAX-RS code

Background – JAX-RS

I’ve been working on a project that uses JAX-RS – the Java API for RESTful web services. If you don’t know JAX-RS, you write web services in Java using annotations to specify what REST endpoint a Java method implements.

For example, you can use @Path annotations on a class to define the root URI for methods in the class, and then use annotations like @GET, @Produces(MediaType.APPLICATION_JSON) and @Path on the individual class methods to define the endpoints that they implement.

The problem?

Reading from code to the web service is straightforward enough. By which I mean, if I’m looking at a Java method, it’s easy enough to look at it and know what endpoint it is implementing.

Going the other way can be a little trickier.

Once a project gets bigger, you can have REST endpoints spread around a large number of classes. And methods can inherit attributes from other classes than the one they’re in, through annotations like @Parent.

What if I’m using one of the project’s REST APIs, and want to look at the source for the method that’s handling it, whether to extend it or fix a bug? How can I remember which method in which class is responsible for the REST endpoint I’m using?

Using Reflection

Documentation is one way. As I develop the code, maintain a list of the mapping of Java methods to web services endpoints. And keep that up-to-date as I make any changes to the code.

But that’s very manual, and doesn’t seem very smart.

This got me thinking yesterday evening. I’d not used Java Reflection before, but thought it must be possible to work it out from the Java annotations in the same way that my JAX-RS provider must.

So I spent a bit of time trying it out and thought it might be useful to share what I came up with. It’s not terribly elegant or efficient. It’s the result of a few hours tinkering. But it shows the basic idea, and that seems useful enough to warrant sharing.

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Posted in code | 1 Comment »

My first experience using BlueVia APIs

Sunday, October 2nd, 2011

I wrote yesterday about a quick hack I did at Over The Air using the BlueVia API. I thought it was worth a quick post to show just how simple it was.

Read yesterday’s post for background to the idea behind the hack, but in essence, what I wanted was:

  • monitor the location of my mobile phone
  • send an SMS to a different mobile number when my phone goes into a predefined known area

BlueVia provides an API that let me doing this using network operator data. In other words, nothing needs to run on my phone itself as location data is obtained from where O2 thinks my phone is.

This means there is no battery-life impact on the phone for this monitoring.

It also means this will work with any phone – from iPhones and Androids to cheap feature phones.

The whole thing took me less than an hour and needed only 90 lines of Python.

This is how I did it.

(more…)

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Posted in code | 8 Comments »

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