Output directory versus embedding data

Replica operations, such as replica creation and synchronization, as well as data extraction, involve data transfer. If you do not set an output directory for the geodata service, the data is transferred embedded within the messages sent and received by the server. This is subject to a maximum message size limit, which is 5 MB by default.

If you plan on creating large replicas, synchronizing large numbers of edits, or extracting large amounts of data, it is recommended that you set an output directory. Contents are uploaded and downloaded from the output directories independently of the service messages. This allows you to perform these larger operations without exceeding message size limits. In some cases, it will also reduce the total amount of data transfer needed to complete the operation.

Geodata service allowed operations

By default, the Query and Extract operations are enabled. With these operations, you can perform read-only actions such as extracting copies of data or performing queries from a published geodatabase. If you have ArcGIS Desktop and an ArcGIS Server Standard edition license, you can use the data extraction command in ArcMap to extract copies. Replication, which exposes the ability to update the published geodatabase, is not enabled by default. You can enable replication on the Service Editor dialog box in ArcGIS Desktop. To perform queries, you must write code using the software development kit (SDK).

Implementing security

When publishing geodata services for access over the Internet, you might want to enable HTTP authentication for security reasons. This requires clients to log in when attempting to access the service.

Messages should be encrypted, since they will include login information. You can use an encrypted communication channel, such as HTTPS, to do this.

Techniques for creating replicas from geodata services

Several tools and options are available for creating replicas from geodata services. The most appropriate method depends on the situation.

If you can connect to the geodatabase locally, use the local connection to specify the geodatabase to replicate to instead of a connection to a geodata service. If you must use a geodata service, be aware that the operation may time out. By default, the time-out time is 600 seconds per geodata service. You can increase the time-out by setting a new value for The maximum time a client can use a service, in the Service Editor.

If you are creating a replica for a very large amount of data, consider using the Register Existing Data option in the Create Replica wizard in ArcMap. To use this option, the data must already exist in both geodatabases. The option is more efficient, since it doesn't copy data. It simply validates that the data exists and registers the replicas in the geodatabases referenced by the geodata services. To get the data from the source geodatabase to the destination geodatabase, you can do the following:

1. Add GlobalIDs to the data in the source geodatabase before sending to the destination geodatabase.
2. Export the data to an export format. This can be an XML workspace document or even files created using tools from the DBMS.
3. Send it to the destination electronically (for example, using FTP or e-mail) or on media sent through a courier.
4. Load the data into the destination geodatabase.