This information supplements the Establishing a Connection chapter. You connect to an ArcSDE data store indirectly through the ArcSDE server. The underlying data source for the data store is a database, such as Oracle. The ArcSDE server is connected to the data source and mediates the requests that you send it.
You can connect to FDO Provider for ArcSDE in one step if you already know the name of the data store that you want to use. Otherwise, you must connect in two steps.
The minimum required connection properties for the initial call to Open() are server, instance, username, and password. Multiple users can access the data store. However, access is password-protected. The server property is the name of the machine hosting the ArcSDE server. The instance property acts as an index into an entry in the services file. An entry contains port and protocol information used to connect to the ArcSDE server. On a Windows machine, the services file is located in C:\WINDOWS\system32\drivers\etc. Assuming that the instance name is “esri_sde”, an entry would look something like this: “esri_sde 5151/tcp #ArcSDE Server Listening Port”.
An ArcSDE data source may contain more than one data store. For the first call to Open(), a data store name is optional. If successful, the first call to Open() results in the data store parameter becoming a required parameter and a list of the names of the data stores in the data source becoming available. You must choose a data store and call Open() again.
If the data source supports multiple data stores, the list returned by the first call to Open() will contain a list of all of the data stores resident in the data source. Otherwise, the list will contain one entry: “Default Data Store”.
If you know the name of the data store, you can provide it for the first call to Open() and make the connection in one step.