How to access a remote database with Reliance

There are two possibilities:

I. Direct access to a remote database

II. Access to a remote database over a network connection

I. Direct access to a remote database

The first way is to access a remote database directly. The client runtime software directly accesses files of a remote database, opens them and reads data from them.

Requirements:

• Computers must be connected to a network so that directories can be shared.
• The directory containing the remote database's files must be shared for reading and writing.
• The database must be of type "DBase" (Reliance Design | Database Manager | Database | Advanced | Database type).

Solution:

• Share the directory (configure the read and write access for competent users) where the remote database is stored on your server computer.
• Add the respective database to the "Databases" folder (Reliance Design | Project Structure Manager | computer | Databases) under the client computer.
• Configure the properties for the connected database:
  "Primary directory", "Standby directory": a network path to the shared directory of the remote database, e.g., \\DataServer1\DataDbAccess\Data\
  "Connection": "Direct"
  "Sample real-time data": inactive
  "Create archive files": inactive.

Disadvantages:

• The remote database's directory must be shared.
• Slower access to the database.
• More data transferred to the client computer.
• Impossible access to the database if offline.

II. Access to a remote database over a network connection

The second possibility is to access a remote database over a network connection. The client runtime software does not access the remote database's files. Instead, it creates its own local copy of the database and updates it with data acquired from a data server over a network connection. When the database's data is requested, the client runtime software opens the local database's files and reads data from them.

Requirements:

• Computers must be connected to a network so that instances of the runtime software can communicate with each other using the TCP/IP protocol at certain range of TCP/IP ports (the default range is 50001–65535).

Solution:

1. Add the respective database to the "Databases" folder (Reliance Design | Project Structure Manager | Computers | Database) under the client computer.
2. Configure the properties for the connected database:
   "Primary directory", "Standby directory": the local database's directory; can be blank – in this case, the "Data" subdirectory of the visualization project will be used (the project should be stored on the computer's local hard disk).
   "Connection": "Network"
   "Delete oldest archive files": as needed – enables you to limit the number of archive files maintained on the client computer.
3. Define a network connection with the data server computer.
4. Add the respective database to the "Databases" folder (Reliance Design | Project Structure Manager | computer | Network connection groups | network connection group | network connection | Databases).
5. Configure the properties for the network-connected database:
   "Limit downloaded archive file count": as needed – enables you to limit the number of archive files downloaded to the client computer when there are no files yet.
   "Data update interval": specifies the time interval used by the client runtime software for requesting the data server for updates.

Advantages:

1. The remote database's directory need not be shared.
2. Faster access to the database.
3. Less data transferred to the client computer (transferred data is compressed).
4. Possible access to the database if offline.

Therefore, we recommend accessing a remote database over a network connection.

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