How to discover JS errors in production code in 5 min

Today I was pulled into a customer call where some customer complained that browser froze for him and the UI kept showing Processing.... . Now as usual I was asked to hunt if it was a server issue or did this customer had any errors. I checked from new relic and from haproxy logs but didnt found any. Then it occured to me what if its a JS error, there was no way to find it out. Then I remembered that New relic had a Beta product to detect JS errors. I went an enabled it from Browser->AppName->settings and within 10 min the errors started flowing.

Good news is that there arent that many errors but in entire day there were almost 150 of them. But for a java guy this is good info and now I can hunt the UI team to fix them.

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RabbitMQ java clients for beginners

Here is a sample of a consumer and producer example for RabbitMQ. The steps are Download Erlang Download Rabbit MQ Server Download Rabbit MQ Java client jars Compile and run the below two class and you are done. This sample create a Durable Exchange, Queue and a Message. You will have to start the consumer first before you start the for the first time. For more information on AMQP, Exchanges, Queues, read this excellent tutorial http://blogs.digitar.com/jjww/2009/01/rabbits-and-warrens/ +++++++++++++++++RabbitMQProducer.java+++++++++++++++++++++++++++ import com.rabbitmq.client.Connection; import com.rabbitmq.client.Channel; import com.rabbitmq.client.*; public class RabbitMQProducer { public static void main(String []args) throws Exception { ConnectionFactory factory = new ConnectionFactory(); factory.setUsername("guest"); factory.setPassword("guest"); factory.setVirtualHost("/"); factory.setHost("127.0.0.1"); factory.se...

Jersey streaming binary data

In the previous post I showed how you can post binary data to a jersey REST api. You can also use Jersey to serve files, although its better done by apache or nginx but sometimes you might want to serve thumbnails stored in a database out of a service and put varnish in front of the REST api to cache the thumbnails. This is just a demonstration of using jersey to serve binary data in streaming fashion. @Path("/download-service") public class DownaloadService extends SecureRestService { private static final AppLogger logger = AppLogger.getLogger(DownaloadService.class); @POST @Produces(MediaType.APPLICATION_OCTET_STREAM) public StreamingOutput getThumbnail( @FormParam("securityKey") final String securityKey, @FormParam("guid") final String guid) throws JSONException { return new StreamingOutput() { @Override public void write(OutputStream out) throws IOException { try { if (!isAuthorized(securityKey)) { response.sendErro...

Spring 3.2 quartz 2.1 Jobs added with no trigger must be durable.

I am trying to enable HA on nodes and in that process I found that in a two test node setup a job that has a frequency of 10 sec was running into deadlock. So I tried upgrading from Quartz 1.8 to 2.1 by following the migration guide but I ran into an exception that says "Jobs added with no trigger must be durable.". After looking into spring and Quartz code I figured out that now Quartz is more strict and earlier the scheduler.addJob had a replace parameter which if passed to true would skip the durable check, in latest quartz this is fixed but spring hasnt caught up to this. So what do you do, well I jsut inherited the factory and set durability to true and use that public class DurableJobDetailFactoryBean extends JobDetailFactoryBean { public DurableJobDetailFactoryBean() { setDurability(true); } } and used this instead of JobDetailFactoryBean in the spring bean definition <bean i...

Programming fun at startup

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