CODEWITHSUNDEEP
azureazure-worker-rolesazure-web-rolesazure-configuration
Andrey Zh.
Andrey Zh.

Reputation: 47

Apply configuration to worker role instances from web role

Good day,

I would like to ask a conceptual question that has been tearing my mind for a while. There is no right or wrong answer here, probably, but I hope to get better understanding of my options.

Situation: I have a Windows Azure Application. It consists of ONE Web Role with ONE instance and ONE worker role with TWO instances.

The main focus is on the worker role. It implements Quartz.NET scheduler to perform a task of getting information from a CRM system, making a table out of it and uploading to FTP server, say, every 8 hours. Very simple, nothing fancy.

The web role is used for manually triggering the job if someone needs it to run between 8 hour intervals. Simple user interface with pretty much one button.

However I would like to have a possibility to make it possible to change some configuration options of the worker role from the web role. For example credentials of destination FTP server and schedule of the job e.g. make it run hourly instead of 8 hours. The configuration DOES NOT need to persist if role goes offline. At the moment config is one in a static class.

This wouldn't seem a problem if I was running one worker role instance: I would send a message from web role via queue and change some static variables in the worker role, for example. But what confuses me is the message queues can be only picked up by one role instance, not both at the same time. So I will end up having the job run every 8 hours in one instance and every hour on another.

Is there any way to notify both instances that configuration needs to change?

Upvotes: 0

Views: 784

Answers (2)

David Makogon
David Makogon

Reputation: 71130

There are several ways you could accomplish this. Let me offer two, aside from what @Gaurav suggested:

  1. Windows Azure configuration settings. If you store your ftp server name and time interval as configuration settings, and then change the configuration, each role instance can capture and handle the RoleEnvironment.Changing event, and take action based on new settings.
  2. Service bus pub/sub. You can have each role instance subscribe to a configuration change topic. Then, whenever you have a change, publish the change to the topic, and each instance, being subscribers, will receive the message and act accordingly.

Upvotes: 1

Gaurav Mantri
Gaurav Mantri

Reputation: 136366

One possibility would be to do a "PEEK" at message by your worker role instances instead of "GET" message. That way the message will remain visible to all the instances. Obviously the challenge there would be when to delete the message. Other alternative would be create a separate queue for each worker role instance (you can name the queues so that each worker role instance would actually GET the message from the queue intended for that instance e.g. if your worker role instances are say WorkerRole1_IN_0, WorkerRole1_IN_1, you could name your queues like workerrole1-in-0, worker-in-1 and so on). Just thinking out loud :)

Upvotes: 0

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