The Data Server is an option when it is not desirable, or possible, to directly connect the Display Viewer Application, Display Viewer Applet or Display Server to data sources. Select the Data Server tab in the Application Options dialog to configure your Data Server(s).

The Data Server uses EII and XML technologies to gather, federate and distribute information from disparate data sources based on information currently in demand. It also caches the data so that multiple demands are delivered to any number of clients - without need of subsequent data queries. These important factors greatly enhance processing speed. Because the Data Server can exist behind firewalls, it also greatly simplifies and strengthens the secured delivery of information to clients beyond the firewall.

The Data Server can be used to serve data to the Display Viewer Application, Display Viewer Applet and Display Server. See the Deployment section for more information.

The following scenarios, or a combination of them, would indicate that one or multiple instances of the Data Server would be useful.

Data Access
In some cases the data source resides in a sub-network where it is not possible or desirable to connect directly. For example, you may have a data source that communicates via a TCP/IP port that is not exposed across a security firewall. In this case, the Data Server would exist behind the firewall and connect to the chosen display technology via HTTP or an available exposed port. In most cases, at least one Data Server must be configured if the Display Viewer applet is used. Applets are restricted to making connections back to the webserver host and will throw an exception if connection attempts are made to any other host.

Data Centralization
While a direct TCP/IP connection to the data sources may be possible, it may not be desirable for each data source and each client. For example, with a Display Viewer Application deployment you might not want a direct TCP connection from each client to every data source. In this case, the Data Server could act as a proxy by directly connecting to all data sources and providing data to each Java application client.

Data Reduction/Aggregation
In some cases, there may be a lot of raw data that does not need to be sent except upon demand. Using the Data Server in this situation can reduce network traffic by performing data calculations from within a sub-network and providing either only the aggregated data or raw data on demand to the chosen display technology. For example the Data Server may publish an average metric over all servers in a subnet, but provide raw data on drill down to a selected server.

Scalability
The Data Server has several data processing features including: an in memory data cache, a persistent alert rules engine, and the ability to perform data calculations. This processing load can be scaled out by dividing the labor across multiple Data Servers that will connect to the chosen display technology.

High Availability
It is possible to designate one or more backup Data Servers to take over during a failover event when an Enterprise RTView client discovers that the current Data Server is no longer accessible. Backup servers may be run in hot standby mode (default) or warm standby mode (designated as a command line option). In hot standby mode all global variable definitions, as well as cache and alert definitions, are loaded and activated at start up. In warm standby mode none of these actions are performed, thereby avoiding the overhead of maintaining Alert and Cache data sources until the backup server has become the primary.

You can specify a primary Data Server, as well as one or more backup Data Servers, for the Display Builder, Display Viewer Application and Display Server. In the Display Builder, select Tools>Options and click on the Data Server tab or utilize -dataserver command line options when launching Display Builder, Display Viewer Application or Display Server.

At startup, the client will connect to the primary server if available, otherwise it will connect to the backup server. If neither is available, the client will periodically retry connecting to both. If the client connects to either the primary or the backup, and later the connection is lost, it will then try to connect to the other server. If a client connects to a backup server and later the primary server becomes available, the client will not switch to the primary unless the connection to the backup server is lost.

NOTE: All servers specified should use the same initialization files (*OPTIONS.ini) and should have access to the same external data sources, so that displays will appear the same regardless of which server is connected.

Running the Data Server

You can run the Data Server as an application, a daemon process, or in the background as a Windows Service. NOTE: The first time you run the Data Server you must run it as an application to configure the initial settings.

To run the Data Server as a daemon process, you must run it from a Windows Command Prompt or UNIX terminal window and the -daemon parameter must be the first command line argument given.

Several command line options are supported for the Data Server. Java options specified in RTV_JAVAOPTS will be used by the run_dataserver scripts. NOTE: These options will not be used when the Data Server is started from the Windows Start menu.

Data source specific options are read in from initialization files created in the Display Builder. For information on creating initialization files or command line options for your data source, refer to Application Options or Command Line Options under the Data Sources section of this documentation.

Run the Data Server: Windows or UNIX

Windows			UNIX
From the Windows Start Menu: Select Start-->Programs-->Enterprise RTView Data Server NOTE: When you start the Data Server from the Windows Start menu, it runs from the demos directory. The Data Server will try to read initialization (.ini) files and resolve XML sources containing relative paths from that directory. To start the Data Server in another directory, you must run Enterprise RTView from a command window. NOTE: It is possible to specify a directory for your initialization files.	From a Command Prompt window: Select Start-->Programs-->Enterprise RTView--> GMS Command Prompt In the command window type: run_dataserver		In an initialized terminal window type: run_dataserver

To begin serving data, click Start Serving Data. Click Stop Serving Data to end this process. If you configure the Data Server to output to an XML file, when you start serving data information will be added to the output XML file each time new data is received for each attachment in all of the specified data configuration files. If you configure the Data Server to output data via socket, when you start serving data the Data Server will receive data requests from Enterprise RTView clients (Display Builder, Display Viewer Application, Display Viewer Applet) indicating what data is needed for currently running displays.
 

Server Modes
This information must correspond with information entered in the Application Options - Data Server dialog. NOTE: By default, the Data Server starts in File Mode. If you change the Server Mode, then you must save the configuration and restart the Data Server.

File
Data redirected from configuration files will be output to an XML file. NOTE: The XML data source is never redirected through the Data Server when you output data to a file. When you start serving data, information will be added to the output XML file each time new data is received for each data attachment in all of the specified data configuration files.

Output File Name - Name of file output by the Data Server containing data from specified configuration files. Default output file name is rtvdata.xml.

Data Configuration Files
Specify which data configuration (.rtv) file(s) will be used to generate the output XML file. Data configuration files are display (.rtv) files created in the Display Builder that contain attachments to data you want to redirect through the Data Server.

Data Configuration Files	Add - Add a data configuration file to the list. If a data configuration file is added while the Data Server is serving data, it will start serving data for attachments in that file as soon as new information becomes available.
	Remove - Remove the selected data configuration (.rtv) file from the list. If the Data Server is serving data when a file is removed, it will stop serving data for that file immediately.
Substitutions	To add or edit a substitution on a specified data configuration (.rtv) file, double-click in the corresponding field of the Substitutions column.

Socket
Data requested by Enterprise RTView clients will be output via socket. When you start serving data, the Data Server will receive data requests from Enterprise RTView clients indicating what data is needed for currently running displays. NOTE: By default the Enterprise RTView client will connect directly to the XML data source, while all other data sources are redirected through the Data Server. For information on redirecting the XML data source, see Application Options - Data Server.
 

Port - Specify the port over which the Data Server will communicate with Enterprise RTView. You do not need to specify a port if you are using the default: 3278.

Use Secure Sockets - If selected, a secure socket layer (SSL) will be used. Enterprise RTView clients may connect directly via socket or through the intermediary Data Servlet using HTTP or HTTPS requests to receive data. NOTE: Using the servlet requires a separate installation process, see the Data Servlet section for details.

Use Client Credentials for Database Login - Pass Enterprise RTView login information into all data sources that have the Use Client Credentials option enabled. NOTE: Use Client Credentials for Database Login only works in Socket mode. Some data sources do not support this feature. For information on Application Options for your data source, refer to the Data Sources section of this documentation.

Send Changed Data Only - If selected, data will be sent only when it has changed. If you want to continuously plot data that has not changed in the trend graph, deselect the Send Changed Data Only checkbox to send all the data regardless of whether or not it has changed. NOTE: Sending all data can lead to performance issues given the amount of information that will be sent over the socket.

Preload Data for Configuration Files
You may specify configuration files for data that you want the Data Server to preload so it will be immediately available to any clients that request it.

Data Configuration Files
Specify which data configuration (.rtv) file(s) will be preloaded by the Data Server. This data will be immediately available to any clients that request it later, and will be updated during Data Server updates. Data configuration files are display (.rtv) files created in the Display Builder that contain attachments to data you want to redirect through the Data Server. Enabled if the Preload Data for Configuration Files flag is selected.
 

	Add - Add a data configuration file to the list.
	Remove - Remove the selected data configuration (.rtv) file from the list.

Console Options

Show Data in Console - If selected, the Data Server Console will print out a line for each piece of data that is being served.

General Options

Start/Stop Serving Data - Start or stop serving data.

Save Configuration - Save settings to an initialization file (DATASERVER.ini), which will be used next time you run the Data Server. NOTE: Unless you specify a directory for your initialization files, you must run the Data Server from the same directory in which the initialization  (.ini) file was saved.

About - Click on to read about Enterprise RTView.

Exit - Exit the Data Server, stop serving data and close the Data Server window.

Console
The Console tab records errors and information. If you select the Show Data in Console check box on the Configuration tab, the console will also display a line for each piece of data that is being served. Click the Clear button to purge all data from the console.

Clients
The Clients tab appears when you start the Data Server in Socket mode. NOTE: By default, the Data Server starts in File Mode. If you change the Server Mode, then you must save the configuration and restart the Data Server.

Connections
This table displays one row for each client that is connected via socket to the Data Server. When clients are connected through the Data Servlet, one connection is shown for the servlet and separate connections are displayed for each HTTP/HTTPS client. If an HTTP/HTTPS client exits under abnormal circumstances, it may not be removed from the table for several minutes.

NOTE: Use the Get Data Server Connection Status function to access information about the status of connections from the Display Builder and Display Viewer Application to the default Data Server and any Named Data Servers. For each client connection, the table contains the following columns.
 

Client ID - A unique number assigned by the Data Server to this client connection. The first client connection is assigned an ID of 1, the second is assigned an ID of 2, etc. The ID for an HTTP/HTTPS client will contain extra digits, starting with the ID of the Data Servlet's connection. For example, if the servlet is assigned a client ID of 1, then the first HTTP/HTTPS client will be assigned an ID of 10001, the next will be 10002, etc. ID numbers will not be reused during a Data Server session.

Address - IP address of the client. Clients running on the same host as the Data Server will display the IP address 127.0.0.1.

Host - Name of the host on which the client is running. Clients running on the same host as the Data Server will display the host name localhost. If a client's host cannot be determined, the IP address will be shown instead.

Duration - Time elapsed in this client's session with the Data Server.

Last Data Sent - Number of characters of XML data contained in this client's most recent update.

Total Data Sent - Number of characters of XML data contained in all updates during this client's session with the Data Server.

Number of Clients
This trend graph (above) displays the number of clients (direct socket, servlet, HTTP/HTTPS) connected to the Data Server over the past hour.