# Enable Federated Search

Use the following procedure to enable the DAH to use federated search with Z39.50, K2, or Ultraseek query servers.

To enable the DAH for federated search

1. Open the DAH configuration file in a text editor.

2. In the `[Federated]` section of the configuration file, configure the following options for a federated search:

   - Set the `Number` parameter to the number of federated modules to use.

   - Set the `DefineTypeCSVsN` parameter to a comma-separated list of the types of query server for each federated module. Do not add spaces after the commas. Number the parameters consecutively, starting at 0 (zero). You can use the following server types:

     - Z39.50 servers must have the type `Z39.50`.

     - K2 servers must have the type `K2`.

     - Ultraseek servers must have the type `Ultraseek`.

   - Set the `LibraryPathN` parameter to the library file for each federated module that you configure. Number the parameters consecutively, starting at 0 (zero). The library file provides the federated search functionality and corresponds to the query server types defined for the federated module.

   For example:

       [Federated]
       Number=1
       DefineTypeCSVs0=Z39.50,K2
       LibraryPath0=federated.dll

3. Configure each of the query server types defined for the federated search module in either the `[DistributedEngineN]` section or the `[IDOLServerN]` section.

   NOTE: Each type of query server has type-specific configuration parameters. Details of these parameters are given in the Distributed Action Handler Reference. See Display Online Help.

4. Save and close the configuration file.

5. Restart the DAH for your changes to take effect.

An earlier type of configuration for DAH federated search for Z39.50 query servers is still supported. Instead of using the `[Federated]` section and configuring the query server types by using the `[DistributedEngineN]` section or the `[IDOLServerN]` section, you can use the following procedure:

1. In the `[Server]` section, set the following parameters:

   - `FederatedLibrary`. Enter the name of the library file that provides the federated search functionality.

   - `FederatedResponseFormat`. Enter the format to use for query responses. It must be a format that the query servers that you want to communicate with accept. The default value is `XML`.

   - `FederatedDefaultRelevance`. Enter the relevance value to display for results that the query servers produce (this is necessary because the servers do not return relevance values for results). The default value is `90`.

   - `FederatedQueryFormat`. Enter `PQF` or `CQL` to indicate the format to use to query the query servers that you want to communicate with. The default value is `PQF`.

     NOTE: PQF (Prefix Query Format) and CQL (Common Query Language) are non-IDOL syntax standards. For more information, refer to the external documentation.

   - `FederatedSecurityType`. Enter the name of the federated security type.

   - `FederatedSecurityKeys`. Enter the security string that contains federated information (user name, group, password).

2. In the `[Engines]` section, increase the `Number` setting by one for each of the query servers that you want to query. Use the `EngineN` setting to list the servers in consecutive order, and to specify their IP addresses and port numbers. Use the `TypeN` setting to specify the type of the servers (Z39.50 servers are type 3). For example:

       [Engines]
       Number=2
       Engine0=123.45.67.89:9949
       Type0=3
       Engine1=123.45.01.23:9787
       Type1=3

   If a Z39.50 server requires authentication, you must also set the `RequiresAuthenticationN` setting to `True` for this server in the `[Engines]` section. For example:

       [Engines]
       Number=2
       Engine0=123.45.67.89:9949
       Type0=3
       Engine1=123.45.01.23:9787
       Type1=3
       RequiresAuthentication1=True

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