How can I create a new site collection in another SharePoint farm

I need to be able to create a new site collectio开发者_StackOverflown from one SharePoint 2010 farm to another. I.e. the user fills out the forms associated in SharePoint Farm 1 and creates a site collection with the specified info in SharePoint Farm 2.

I have considered the following alternatives:

1. Using the Client Object Model (COM), but the highest available object is SPSite, and I need a SPWebApplication object to create a new site collection.
2. Using a built in SharePoint 2010 Web Service, but which one? Neither WebSvcAdmin, WebSvcSiteData, or WebSvcsites seems to be able to do this.
3. Implement a custom web service, but what about authentication?

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You need to use SPWebApplicationBuilder class. But instead of SPFarm.Local use SPFarm.Open(SqlConnectionStringBuilder connectionString, string user, string password)