Significance of the AppPool Identity?

Question

I am trying to deploy SharePoint 2010 web parts. When trying to configure the data source of one of them, it says that the .svc service could not be activated. When I check IIS, the Identity of the service is ApplicationPoolIdentity. When I checked a different
server that deployed the same web parts, it's identity was spAppPool, which is not a user on that server.
So my questions are...
1) Should I change the Identity that's associated with the service that could not be activated?
2) Where is spAppPool? If it was created in IIS, could that explain why I can't find it?
Truth be told, I am uncertain what this is causing, as the logs I've been able to access isn't clear to me. If I have the diagnosis wrong, feel free to say so. Otherwise, I am focused on the scenario that Applcation Pool identity is the issue.
Chris Lee

Answer 1

Hi Chris,
The identity of an application pool is the name of the service account under which the application pool's worker process runs. For every application pool you create, the Identity property of the new application pool is set to
ApplicationPoolIdentity by default.
You can also configure a custom account to serve as an application pool's identity. Any custom account you choose should have only the minimum rights that your application requires. A custom account is useful in the following situations:
When you want to improve security and make it easier to trace security events to the corresponding application.
When you are hosting Web sites for multiple customers on a single Web server. If you use the same process account for multiple customers, source code from one customer's application may be able to access source code from another customer's
application. In this case, you should also configure a custom account for the anonymous user account.
When an application requires rights or permissions in addition to the default permissions for an application pool. In this case, you can create an application pool and assign a custom identity to the new application pool.
For this issue, I suggest you change the Identity of the application pool to the farm account in your SharePoint farm.
If this issue still exists, please provide more information about this error.
For the spAppPool, please check if it is an account in the SharePoint farm.
More information about Application Pool Identify, please refer to the links:
http://www.iis.net/learn/manage/configuring-security/application-pool-identities
http://technet.microsoft.com/en-us/library/cc771170(v=WS.10).aspx
Best Regards,
Wendy
Wendy Li
TechNet Community Support