Objective

The objective of this lab is to gain an understanding of how picos communicate with each other and how they react to those communications.

Reading and Reference

Read the following:

• Persistent Compute Objects
• Events and Queries Links to an external site.

You may find the following resources useful:

• KRL Manual 
• Developer Tips for the Pico Engine 
• Raising Events Links to an external site.

Prerequisites

You should have completed:

• Lab 0: Getting Started 

Implementation Notes

• The best way to use the KRL documentation is to search since you may not always appreciate how it's organized (or isn't).
• People often can't get their ruleset to run because it doesn't parse. Make sure you always parse your ruleset before checking it into whatever system you're using to store it (probably GitHub).
• If your changes don't seem to take effect, the most common cause is likely that GitHub's internal caching is returning the old ruleset even though you've checked in changes. Try waiting 5 minutes, refreshing, and trying again. Alternatively, register your changed ruleset code through the Engine Rulesets page.
• Note that if you have two rules in your installed rulesets that select on the same event, then they will both fire when the pico sees that event.
• You can do this entire lab in one pico. You can do it in your account's primary pico, or you can create a child pico and install the rulesets there. 

Do This

Complete the following in the pico that you installed in the hello_world ruleset of Lab 0. 

1. Create a new channel (pick any name and type you like). 
   1. Send an event to the pico using the new channel and the original (default) channel. 
   2. Do you get the same result on both? Why or why not? 
2. Delete the channel.
   1. Resend the event using the deleted channel. 
   2. What happens? Why?
3. Send the misspelled event ecco/hello to your pico. What do you observe? Why? 
4. Add a new rule to the hello_world ruleset that selects on echo/monkey and responds with "Hello Monkey" unless an event attribute named name is given, in which case it will respond with "Hello " followed by the given name. Hint: use the .defaultsTo() operator. Use the .klog() operator to log the value that is used. 
5. Repeat the previous step using the ternary conditional Links to an external site. instead of the .defaultsTo() operator. 

Deliverables

Turn in the following:

1. URLs for your ruleset(s)
2. Short screencast (< 3 min with sound) showing the results from (4) and (5) above
3. Answers to any questions posed in the preceding "do this" section.