I'm confused about some ESRI terminology.

If I have ArcGIS 10.1 Server installed and we use Enterprise geodatabases with versioning capabilities but we use direction connections does this have anything to do with ArcSDE or SDE?

I know that ArcSDE isn't even installed on our server, but I see ArcSDE experience being requested quite a bit but I never know if they truly are using ArcSDE or that's just what they are used to calling it.

Can someone clear this up for me?

3 Answers 3


"ArcSDE" refers to the API, the network communication protocol, the application server, and the tables and stored procedures registered in a geodatabase. If you have an Enterprise Geodatabase in an RDBMS, you are using ArcSDE technology, even if you never start the application server. "Direct Connection" is always a synonym for "ArcSDE Direct Connect connection" which uses the application server DLLs as an additional thread in the client application, and manages streams the same way an application server would, but locally.


ArcSDE is included in ArcGIS Desktop and ArcGIS Server. You get all the libraries and files needed to be able to connect to a DBMS database when installing ArcGIS Desktop or ArcGIS Server (the SQL Server Native Client is used). When you make a database in your DBMS a geodatabase, you create a set of special system tables (called repository) which makes it possible to implement ArcGIS behaviour and logic within DBMS database.

In order to "make" a database an enterprise geodatabase (aka SDE geodatabase), you need to have ArcGIS Server license. You can also "make" a database to become a workgroup geodatabase (aka SDE Personal) with SQL Server Express. There are some capacity limitations here as well as number of connecting users.

When you use versioning in your enterprise geodatabase, you use ArcSDE functionality that is built within the ArcGIS. It doesn't really matter how you access your geodatabase; if you use DC, then you use libraries that are included with ArcGIS (without installing explicitly ArcSDE libraries). If you would use ArcSDE Application Server connection, you would need to install ArcSDE software to let ArcGIS clients to connect to DBMS geodatabase by using an ArcSDE service.

  • oops I guess you were hitting the save button as I was adding this. ---- it should be noted that this all refers to direct connect sde. application connections require an installation, database registration, and a created instance (in sde). But unless you must have an application server connection (and know why you need that) you are most likely not going to miss it.
    – Brad Nesom
    Oct 3, 2013 at 15:51

ESRI has a pretty decent help section on what ArcSDE services are:

An ArcSDE service, also known as an ArcSDE application server or a three-tiered architecture, conveys spatial data between GIS applications and a geodatabase. The database may be any of the supported database management systems (DBMSs)—Oracle, SQL Server, Informix, DB2, or PostgreSQL.

Compare that to ArcGIS Server definition from wikipedia (couldn't find an updated definition from ESRI oddly enough):

ArcGIS Server is the core server geographic information system (GIS) software made by Esri. ArcGIS Server is used for creating and managing GIS Web services, applications, and data. ArcGIS Server is typically deployed on-premises within the organization’s service-oriented architecture (SOA) or off-premises in a cloud computing environment.1 ...

ArcGIS Server is also used to manage multiuser geodatabases. Multiuser geodatabases leverage ArcSDE technology, implemented on a relational database management system (RDBMS). ArcGIS Server Enterprise supports IBM DB2, IBM Informix Dynamic Server, Microsoft SQL Server, Oracle, and PostgreSQL. ArcGIS Server Workgroup supports Microsoft SQL Server Express R1 and R2.

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