Salesforce can defend two ways: 1) challenge the validity of the patent, or 2) prove that they don't infringe the patent.
Option 1 is harder. Patents are presumed valid. Defendant (Salesforce) has the burden of proof that the patent should be overturned. Salesforce will have to do that for each alleged infringing claim.
Option 2 is easier. Plaintiff (Microsoft) has the burden of proving infringement. Salesforce just needs to show that they aren't infringing claim 1 and then they also aren't infringing claims 2-9.
Salesforce can defend two ways: 1) challenge the validity of the patent, or 2) prove that they don't infringe the patent.
Option 1 is harder. Patents are presumed valid. Defendant (Salesforce) has the burden of proof that the patent should be overturned. Salesforce will have to do that for each alleged infringing claim.
Option 2 is easier. Plaintiff (Microsoft) has the burden of proving infringement. Salesforce just needs to show that they aren't infringing claim 1 and then they also aren't infringing claims 2-9.