DataExchange Basics
An Overview of DataExchange Basics
The following topics explain the core concepts and routine tasks of using DataExchange. Information on working with the engine, logins and DSNs related to DataExchange is included.
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Starting and Stopping Replication
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Starting and Stopping the DX Agent Service
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ODBC Basic Concepts
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Replicating a Database with PSQL Security
Starting and Stopping Replication
Depending on the PSQL product, the DataExchange replication engine runs as a service or a console application. It can be accessed from PSQL Control Center (PCC). This topic covers starting and stopping the engine in all three cases.
As a Service
DataExchange (replserv.exe) runs as a service on the system where a PSQL Server is installed. It is a single executable that runs under the Windows Service Control Manager. It is configured by default to run when the system starts under the LocalSystem account, which should be adequate in most cases. If needed, you can change the account in the Log On tab of the Properties dialog for the service in the Services Control Panel.
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To start the Replication service
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Open the Services Control Panel.
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Select Actian PSQL Replication.
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Do one of the following:
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Select the service and then on the left, click Start.
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Open the service and under Service Status, click Start.
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Right-click the service and select Start.
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To stop the Replication service
1
Open the Services Control Panel.
2
Select Actian PSQL Replication.
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Do one of the following:
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Select the service and then on the left, click Stop.
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Open the service and under Service Status, click Stop.
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Right-click the service and select Stop.
As a Console Application
The DataExchange replication engine (replserv.exe) runs as a console application if PSQL Workgroup engine is installed. The application appears as an icon in the notification area to the right of the Windows Taskbar.
By default, the replication engine starts when the system starts. You can also start it manually.
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To start the replication engine manually
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Select DX Replication Engine from the Start menu.
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To stop the replication engine while running as a console application
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In the Taskbar, right-click the DataExchange icon .
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Select Stop Engine and Exit.
From PSQL Control Center
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To start the Replication service
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Start PCC if it is not already running. (Select PSQL Control Center & Documentation from the Start menu.)
In PSQL Explorer under Engines, the Replication icon shows a red dot to show the replication engine is stopped.
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In PSQL Explorer, expand the Services branch.
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Right-click Actian PSQL Replication and select Start Service.
Under Engines, the Replication icon shows a green arrow to show the replication engine is running.
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To stop the Replication service
1
Start PCC if it is not already running. (Select PSQL Control Center & Documentation from the Start menu.)
In the Replication icon the green arrow shows the replication engine is running.
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In PSQL Explorer, expand the Services branch.
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Right-click Actian PSQL Replication and select Stop Service.
In the Replication icon the red dot shows the replication engine is stopped.
Starting and Stopping the DX Agent Service
DataExchange Agent runs as a service. It can be accessed from PSQL Control Center (PCC). This topic covers stopping and starting the agent as a service and from PCC.
As a Service
The DataExchange executable dxagent.exe runs as a service on the machine where PSQL Server or Vx Server is installed. It is configured by default to run when the system starts under the LocalSystem account, which should be adequate in most cases. If needed, you can change the account in the Log On tab of the Properties dialog for the service in the Services Control Panel.
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To start the DX Agent service
1
Open the Services Control Panel.
2
Select Actian DataExchange Agent.
3
Do one of the following:
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Select the service and then on the left, click Start.
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Open the service and under Service Status, click Start.
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Right-click the service and select Start.
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To stop the DX Agent service
1
Open the Services Control Panel.
2
Select Actian DataExchange Agent.
3
Do one of the following:
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Select the service and then on the left, click Stop.
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Open the service and under Service Status, click Stop.
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Right-click the service and select Stop.
Note Dxagent.exe is not installed with the Workgroup engine.
From PSQL Control Center
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To start the DX Agent service
1
Start PCC if it is not already running. (Select PSQL Control Center & Documentation from the Start menu.)
2
In PSQL Explorer, expand the Services branch.
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Right-click Actian DX Agent and select Start Service.
In the Services branch, the service icon now shows green to show DX Agent is running.
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To stop the DX Agent service
1
Start PCC if it is not already running. (Select PSQL Control Center & Documentation from the Start menu.)
2
In PSQL Explorer, expand the Services branch.
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Right-click PSQL Replication and select Stop Service.
In the Services branch, the service icon now shows red to show DX Agent is not running.
ODBC Basic Concepts
PSQL follows the Microsoft standard for ODBC database connections. According to the standard, applications must connect to databases through Data Source Names (DSNs) defined in the operating system.
Every PSQL database that you expect to access using ODBC must have a Data Source Name (DSN) available on the same computer as the database engine, and (if applicable) another DSN on the client computer. The only exceptions are PSQL tools, which can access remote databases without using DSNs on the client computer. A DSN created on the same machine as the database engine is called an Engine DSN. A DSN created on the client machine is called a Client DSN.
Note PSQL databases that are accessed only through Btrieve do not need DSNs. However, in this case, the database is not visible in PCC nor can it be manipulated using PCC. PSQL recommends using Data Dictionary Files (DDFs) and DSNs with all databases, including ones accessed only through Btrieve, to make them easier to manipulate.
Servers and Clients
Every PSQL Server engine or Workgroup engine includes a client installation. So you can use your server machine to connect to other servers as a client.
PSQL clients can connect to remote machines where a PSQL Server engine is installed.
Data Source Names
In a client-server architecture, each data set must have a well-known name. A DSN is a well-known name for a data set. There are generally three ways to create DSNs:
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Create an Engine DSN from the server console. Workgroup engines require only Engine DSNs.
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Create an Engine DSN remotely from a client machine.
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Create a Client DSN on each client machine.
Components of a Database Name
There are two components of a database name. PSQL uses an internal Database Name (DBNAME) to identify the location of the Data Dictionary Files (DDFs) and the data files for each database. An ODBC Data Source Name (DSN) entry refers to one DBNAME.
You may set up more than one DSN that refers to the same DBNAME. If the physical location of the data files on the server is changed, only the DBNAME needs to be updated. All DSNs remain unchanged.
Replicating a Database with PSQL Security
PSQL provides security models for Btrieve applications. However, an activated database created by DXdeploy does not automatically use security, even if its source database does. You can add security in one of two ways:
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Enable security in PCC before designing a new template for replication.
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For an already activated database, first deactivate the database at all sites. Once PSQL security has been configured, you can then reactivate the database.
For more information about security in PSQL, see the PSQL Advanced Operations Guide.
The following example uses Demodata to show the use of PSQL security with DataExchange.
Deploying Demodata Under PSQL Security
The topic Replication Deployment Using DXdeploy with an XML Descriptor File explains how to deploy the sample database Demodata under the Classic security model. However, if you are using either Database or Mixed security, you must first ensure that Demodata can be deployed successfully.
The following table lists actions required to deploy Demodata. Perform these on both the First Site and the Partner Site before attempting the DXdeploy example deployment.
Replication Site
Database Security Model
Mixed Security Model
First
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Add C:\ProgramData\Actian\PSQL\Demodata as a data file location for DefaultDB
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Add the templates directory as a data file location for DefaultDB. For example, on a 64-bit system this location is C:\Program Files (x86) \Actian\PSQL\Replication\Templates.
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In PCC Configuration for Server Access, turn on Prompt for Client Credentials. You can also do this using the PSQL pvnetpass utility.
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During the example deployment, a login dialog prompts you to log in to DefaultDB. When you enter the user name and password, select the option Save User Name and Password to avoid having to log in for each table replicated.
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After the example deployment finishes, we recommend that you use pvnetpass to remove the saved user name and password. If you choose not to do this, note that any Btrieve application on the secured site has access to all databases associated with DefaultDB.
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Add C:\ProgramData\Actian\PSQL\Demodata as a data file location for DefaultDB
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Add the templates directory as a data file location for DefaultDB. For example, on a 64-bit system this location is C:\Program Files (x86) \Actian\PSQL\Replication\Templates.
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In PCC, click Users for DefaultDB. Right-click the Public group, then click Properties.
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Click the Permissions tab. Grant all permissions for Public, then click OK.
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After the example deployment finishes, reset the permissions for user Public as suits your business requirements.
Partner
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Add C:\ProgramData\Actian\PSQL\Demodata as a data file location for DefaultDB
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Add C:\ProgramData\Actian\PSQL\Demodata as a data file location for DefaultDB
Once you have finished these actions, you can return to the example under Replication Deployment Using DXdeploy with an XML Descriptor File or to your own replication database deployment.