1990354 - Changes in internal HANA Web Dispatcher as of HANA SP9

Symptom

The integration of SAP Web Dispatcher in HANA has changed with SP9.

Other Terms

HANA XS, webdispatcher, sapwebdisp_hdb, SAP Web Dispatcher, internal HANA Web Dispatcher

Reason and Prerequisites

You have installed HANA SP9 or are upgrading from an earlier release to HANA SP9 and are using HANA XS engine for HTTP access.

Solution

With HANA SPS 9 the internal HANA Web Dispatcher is integrated as a native HANA service named "webdispatcher". It replaces the previous standalone executable "sapwebdisp_hdb".
Main Benefits and Changes

• Administration (start/stop) and monitoring (CPU, memory) of the internal Web Dispatcher in HANA Studio.
• Configuration via webdispatcher.ini in HANA Studio or ALTER SYSTEM SQL statement. The previous profile sapwebdisp.pfl is removed, settings are migrated automatically.
• Changed trace file name to webdispatcher_<…>_dev_webdisp.
• The Web Dispatcher admin tool is now accessible at path /sap/hana/xs/wdisp/admin. Log on with a database user that has role sap.hana.xs.wdisp.admin::WebDispatcherAdmin to use it.
• The Web Dispatcher admin tool now manages SSL certificates and other PSEs used by HANA, which supersedes the sapgenpse command line tool. SSL is active out of the box.

Administration in HANA Studio
The internal HANA Web Dispatcher is now visible and can be started and stopped in HANA Studio. You can also monitor memory and CPU usage like for any other HANA process. (Actually, it cannot be started, only stopped. It is started on every host where an XS engine is configured to run. If you want to restart Web Dispatcher you just have to stop it and it is restarted automatically.)
Configuration
Previously the configuration of the Web Dispatcher was stored in file <hostname>/wdisp/sapwebdisp.pfl. Now all profile parameters have to be maintained in the section "profile" of webdispatcher.ini. This INI-file can be accessed via the SAP HANA studio or with the following SQL command:

ALTER SYSTEM ALTER CONFIGURATION('webdispatcher.ini','system') SET('profile','<profile parameter name>')=
    '<profile parameter value>' WITH RECONFIGURE

If you are upgrading from an old version, the user-defined parameters in <hostname>/wdisp/sapwebdisp.pfl will be automatically migrated to webdispatcher.ini.
Note one difference: The INI file is case insensitive and by default all parameter names are in lower case. So when you use parameters from the Web Dispatcher documentation for the internal HANA Web Dispatcher, you may convert them to lower case, but only in the HANA INI file. Elsewhere, Web Dispatcher parameters are still case sensitive.
The webdispatcher.ini contains only a reduced set of parameters that are relevant for configuration. Several parameters that are usually not changed are now set implicitly, but of course you can still change them by setting them explicitly in webdispatcher.ini.
If you change dynamic parameters via HANA Studio, the new values will become active directly and no restart is required. Unfortunately not all parameters are dynamic, but the most important parameters are dynamic - for example wdisp/system_xx, icm/server_port_xx or rdisp/trace. It will be written into the webdispatcher_<..>.trc trace file whether the parameter you changed was dynamic or requires a restart. In case a restart is required, just stop the process in HANA Studio and it will be automatically restarted.
Trace
Previously the Web Dispatcher created the trace file dev_webdisp, which does not follow the standard HANA trace file format. This file was renamed to webdispatcher_<...>_dev_webdisp. It is still the main functional trace file of the Web Dispatcher.
In addition there is a second trace file webdispatcher_<...>.trc. It is written by the HANA process wrapper and contains information on the HANA integration, like start/stop, configuration changes etc.
The Web Dispatcher trace level (for webdispatcher_<...>_dev_webdisp) can be changed in two ways: First you can modify the well-known parameter rdisp/TRACE in the "[profile]" section of webdispatcher.ini. Possible values are: 0, 1, 2, 3. The parameter is dynamic, therefore the change will become active without restart. Alternatively you can change the trace level by changing the HANA trace level (e.g. FATAL, ERROR, INFO, DEBUG) for component "dev_webdisp" in the Database Trace section WEBDISPATCHER. The trace of the wrapper process can be changed with component "webdispatcher".
Hint: For many tasks a newly created header trace is most efficient, because it only contains the request data and no info on the internal workings of Web Dispatcher. The header trace can be enabled by setting parameter icm/HTTP/trace_info = TRUE in the "[profile]" section of webdispatcher.ini. It is also implicitly switched on by trace level 2.
Web Dispatcher Administration UI
The Web Dispatcher Administration can be used for specific monitoring and administration tasks. You can start it with the URL /sap/hana/xs/wdisp/admin. To use the Admin UI you have to authenticate yourself using a database user. This user requires one of the following roles: sap.hana.xs.wdisp.admin::WebDispatcherAdmin or sap.hana.xs.wdisp.admin::WebDispatcherMonitor (for monitoring use only).
SAP Web Dispatcher is a generic component being re-used in HANA. The Administration UI contains some functionality that makes no sense for the use case as internal HANA Web Dispatcher. Please do no use the following sections and features:

• "Hostname Buffer"
• "Statistic"
• "MPI Status"
• "Admin Handler"
• "SSL End To End Dispatching"
• "Session Dispatching"
• "Backend System Info"
• "Monitor Application Servers"
• Dynamic modification and activation/deactivation of ports in "Active Services"
• "Enter Maintenance Mode" in "Monitor"

This functionality will be disabled in a maintenance revision of SP9.
SSL Certificates
Web Dispatcher now creates self-signed SSL certificates out of the box. An SSL port using this certificate is opened by default. The port number is 43<nn>, where nn stands for the instance number.
A valuable addition to the Web Dispatcher Administration is the PSE management. Using the PSE management, you can now generate a signature request for a certificate authority (CA) or import CA responses without needing to use the arcane sapgenpse command line tool.

Header Data

Released On	17.11.2014 15:56:10
Release Status	Released for Customer
Component	BC-CST-WDP Web Dispatcher
Other Components	HAN-AS-XS SAP HANA Extended Application Services
Priority	Recommendations / Additional Info
Category	Special development