State Service的作用:

The State Service service application is used to maintain state. This is one of those goofy .NET
developer things which is the equivalent of writing on your hand. It holds the information
temporarily while you use it and then it goes away. Some people assume this isn’t necessary but even
out-of-the-box features use it so just Go ahead and provision it to save looking up the error messages
later.

State Service在sharepoint中是无法通过图形化界面安装的，必须通过powershell命令来完成安装：

1. At the prompt, type the following and press Enter:
New-SPStateServiceApplication -Name "State Service Application"
2. At the prompt, type the following and press Enter:
Get-SPStateServiceApplication| New-SPStateServiceApplicationProxy
-defaultproxygroup
3. At the prompt, type the following and press Enter:
Get-SPStateServiceApplication| New-SPStateServiceDatabase -Name
"State_Service_DB"
4. At the prompt, type the following and press Enter:
Get-spdatabase | where-object {$_.type -eq
"Microsoft.Office.Server.Administration.StateDatabase"} |
initialize-spstateservicedatabase