What is a geodata service?
A geodata service allows you to access a geodatabase through a local area network (LAN) or the Internet using ArcGIS Server. The service exposes the ability to perform geodatabase replication operations, make copies using data extraction, and execute queries in the geodatabase. A geodata service can be added for any type of geodatabase including ArcSDE geodatabases, personal geodatabases, and file geodatabases.
Geodata services are useful in situations where you need to access geodatabases in remote locations. For example, a company may want to set up ArcSDE geodatabases to manage data in its Los Angeles and New York offices. Once created, each office can publish its ArcSDE geodatabase on the Internet using a geodata service. The geodata services can then be used to create replicas for the ArcSDE geodatabases. With geodatabase replication, the geodata services can also be used to periodically synchronize the changes in each geodatabase over the Internet.
Before working with geodata services, you should have a basic understanding of how geodatabases, geodatabase replication, and data extraction work. The topic Understanding distributed data in the ArcGIS Desktop Help is a good starting point. Additionally, it's helpful to have some experience performing replication and data extraction in the ArcGIS Desktop environment before attempting these operations with ArcGIS Server.
Preparing the geodatabase in ArcGIS Desktop
The first step in publishing any GIS service is to create the GIS resource that it will reference. For geodata services, the resource is either an ArcSDE geodatabase, a personal geodatabase, or a file geodatabase. You can create any of these types of geodatabases using ArcCatalog. In the Data Management section of the help, you can find much information on geodatabase design and creation. Additionally, ESRI Press has published several books on architecting effective geodatabases.
If you plan on using your geodata services for geodatabase replication, you must make sure that the data is configured properly and is from an ArcSDE geodatabase. See the topic Preparing data for replication in the ArcGIS Desktop Help for additional information.
Publishing a geodata service
Two types of publishing operations can yield a geodata service: publishing from a geodatabase directly and publishing a geodata service with a map service. Once published, the geodata service can be used for synchronizing replicas or working with a geodatabase in a Web application or Web service.