Custom reporting is still not yet possible in Dynatrace SaaS. I recommend you upvote the following Requests for Enhancements to add this feature. See links below
I think the request is how would I chart (or report) method invocations. Let's say I have a specific method createAccount(). When the service call comes in, it determines if an account exists and if it doesn't it creates a new account. The service could be exampleAccountService. Dynatrace would let me chart this service, but what if I want to chart how many new accounts are created?
In AppMon, I'd create a measure on that method (creating a sensor behind the scenes) and then the software would start collecting that data where I could then create a dashboard that could be used for viewing or as a template for a report (adhoc or scheduled).
I know you can create a custom 'service detection rule'. Would I need to create that and then chart that service?
It seems like Dynatrace has separated out some functionality:
As for reporting, it seems like you'd need to build a custom dashboard off of this and then wait for the export as pdf feature... if you want csv/xls it looks like you'll need to write your own script to use the rest interface and have it parse the json into your format of choice.
Do I have that right?
Yes you are right! If the service i.e. exampleAccountService is not created automatically with its service methods (e.g. createAccount()), then yes you will need to create the custom service and then specify the methods that should be captured for the custom service. I will then mark the methods I care about (createAccount()) as a key request and then chart on it using custom charts or use the API to pull the data using your custom script. Custom reporting feature to save as pdf or xls/csv is still not available at this time.