With Service Based Architecture, you can perform the following actions:

• GET - Obtain a list of objects or details on a specific object.
• POST - This action is used for the creation of an object
• PATCH - When an update needs to be done, this HTTP Request Type is used.
• DELETE - This is used when an object needs to be deleted

Here is what is exposed to Service Based Architecture with Dynamics GP 2015 RTM:

• Administration
  • Countries
  • Currencies
  • Payment Terms
• Companies
• Financials
  
  • Checkbooks
  • Currency Accounts Setup
• Inventory
  
  • Classes
  • Item Currencies
  • Item Price Lists
  • Items
  • Item Sites
  • Item Vendors
  • Lot Categories
  • Price Groups
  • Price Levels
  • Sites
  • Transaction Headers
  • Transaction Lines
  • Transactions
  • Unit of Measure Headers
  • Unit of Measure Lines
  • Unit of Measures
• Modules
• Products
• Purchasing
  
  • Payables Transactions
  • Requisitions Transaction Headers
  • Requisitions Transaction Lines
  • Requisition Transactions
  • Vendor Addresses
  • Vendors
• Sales
  
  • Classes
  • Customer Addresses
  • Customers
  • Receivables Transactions

Not all of the above actions (GET | POST | PATCH | DELETE) are available for each of these objects.