Configuring the topology of components

This page is obtained by clicking the Add new Segments button in the Configured Segments page. It facilitates the definition of the segment topology. 

The eG Enterprise suite's patented correlation technology is dependent on the specification of topology information. Topology indicates how components are interconnected and which components rely on others for their functioning. The interconnections can represent either of the following:

• Physical connections (e.g., a web server connected to a network router) 
• Logical dependencies (e.g., a web server using a web application server). 

Each interconnection is associated with a direction. The direction signifies cause-effect relationships (if any) between the connected components. To define the topology, do the following: 

• The name of the new segment has to be specified in the Segment name text box.
• Using this screen, you can also associate the segment being created with a zone, by selecting the zone from the Associated to the zone list. If the segment is not to be associated with any zone, then select None from the Associated to the zone list.
• Select a display image relevent to the segment, from the Choose display image dropdown.
• The type of component has to be first selected from the Start component type list box available at the top left corner. This list box will list only those component-types in the environment/zone that have been managed by the eG Enterprise system. Also, if component groups have been configured using the eG administrative interface, then a Group option will also be available in the Start Component list. While configuring large topologies, you can use one/more of the configured groups to represent a load balanced group of servers which share the same inter-dependencies with other infrastructure components. Once a component-type is chosen, select a component of the chosen type from the Associated Components list. Similarly, if the Group option is chosen, then all configured groups will be available for selection in the Associated Components. Then, from the Other Components list choose the component/component group with which the previously chosen component/component group is to be associated.

  When configuring the topology of a segment that is not associated with a zone, all the managed components and fully-configured groups in the environment are candidates for inclusion in the current segment. In the case of infrastructures comprising of a large number of components/groups, selecting specific components/groups from the Associated Components list and the Other Components list could prove to be a tedious task. To enable administrators of such environments to easily view the components/groups list and quickly make a selection, eG Enterprise, by default, displays only the independent components/groups in the Associated Components list and the Other Components list. In other words, by default, components/groups that are already a part of other segments will not be available for inclusion in a new segment. However, if a single component/group features in multiple segments, this default setting can be overridden - i.e., while configuring such segments, you can switch on the Use components from other segments flag in this page. By default, this checkbox is deselected. By selecting it, you can ensure that components/groups that are already a part of other segments are also available for inclusion in the new segment.

  In the case of a segment that is associated with a zone, the following components are available for inclusion in the segment:

  • Independent components/groups that are available in the associated zone
  • Components/groups that are part of other segments in the associated zone

  By default however, the independent components/groups in the associated zone will alone be displayed in the Associated Components list and the Other Components list. Accordingly, the Use components from other segments option will be unchecked, by default. If you want the new segment to use components/groups from other segments in the zone, select the Use components from other segments checkbox. When this is done, all the components/groups in the associated zone, though part of other segments in the zone, will appear in the Associated Components list and the Other Components list.

• The topology of the segment must be configured left-to-right, with the left most node(s) representing entry points through which users access the web services offered in the target environment.

• The segment topology is configured step-by-step, with all the dependencies of one of the components/groups in the environment being specified at each step. The eG Enterprise system supports two types of dependencies, namely: 

• The Connects >> dependency, which typically indicates flow of data (e.g., a physical connection between a web server and a network router). This dependency can be attained by selecting a particular component/group and then clicking the Connects >> button. 

• The Uses >> dependency, which refers to a logical dependency (e.g., a web server and a web application server, a web application server and a database server, etc.). This can be achieved the same way as before but by clicking the Uses >> button. 

The key difference between the two forms of dependencies is that when one component/group Uses >> another, problems with the latter can actually result in problems in the former. With the Connects >> dependency, there are no such cause-effect relationships between the components.

• All these dependent components will be available in the Associated components list box. Each entry in this list box is of the form "host:port:direction:componenttype", where the direction is either "L" or "N". While "L" indicates a Uses >> dependency, "N" indicates a Connects >> dependency.

  For better understanding, assume an infrastructure that has a network node (N/w), a web server (WS), an application server (APP) and a database server (DB). A user enters through the network node to the web server (WB). The web server sends the requests to the application server (APP) that in turn communicates with the database server (DB). The dependencies that exist between the three are as follows:

  • N/W connects to the WS: This is because a physical connection exists between the network node and the web server and problems  associated with each component are typically independent.

  • WS uses APP: This connection reflects the software dependency of a web server on an application server for processing requests.

  • APP uses DB: The application server depends on the database server. Hence, the Uses relation exists between these two components, indicating that a problem with the database server can ripple through and affect the application server.

  At each step, as the dependencies are specified by the administrator, the Segment preview section at the bottom displays the current segment topology configuration. If you want to focus on the links emerging from or leading to a particular component in the topology, all you need to do is to move your mouse pointer over that component/group in the Segment preview. The type and IP:Port of the component in focus will then be displayed in the Highlighted Component box at the bottom of the Segment preview section, and the relationships specific to the component will be highlighted in the preview. Likewise, moving your mouse pointer over a group in the preview will naturally reveal the group name in the Highlighted Component box, and also the relationship the group shares with other elements in the topology. Moreover, in order to help you view and analyze the configured topology better, the Segment preview section provides a special toolbar comprising of a wide variety of viewing options. This toolbar is also available while previewing the segment/service topology in the eG monitor interface.

  Note:

  The special toolbar will be available only if your browser supports the Java plugin Sun JRE 1.3.x and above. In case of browsers that do not support this plugin, the toolbar options are still available, but in the form of a shortcut menu that appears upon right-clicking anywhere in the Segment preview section.

  Each of the options provided by this toolbar is discussed in great detail, below:

  Tool	Purpose
  	Helps to zoom in and zoom out the topology representation.
  	You can change the position of any server representation in your topology by cliking, dragging, and dropping that representation. Once done, you can click on this icon to save the change in position.
  	As stated earlier, you can reposition any component in the Segment Preview by clicking on it and dragging it to the desired position. To restore the component(s) so shifted to their original positions, click on this icon.
  	Click here to view the topology in a new window.

  The feedback provided by the segment preview can be used by the administrator to refine the topology specification. The << Remove button can be used to delete any of the configured dependencies from the topology. On clicking on the Delete Segment button, the entire segment topology gets deleted. Care should be taken while using this button, else the user will have to configure the segment topology from the beginning.

In case of a segment associated with a zone, a few additional options are provided in this page. A section named ASSOCIATION gets appended to the bottom of this page, which provides a hyperlink to the zone that includes the segment. Using this Zone mapping, you can temporarily halt segment configuration, immediately switch to the configuration page of the chosen zone, make modifications to the zone composition, and return to this page to resume segment configuration. This is useful in situations where a component required for building the segment is not available in the associated zone. Under such circumstances, you can use the hyperlinked zone name against Zone mapping to add the desired component to the zone, and then proceed to include the component in the segment. This hyperlink thus saves administrators the time and trouble of manually shuttling between the segment and zone configuration pages.

Once a segment is fully configured, a Disassociate hyperlink also appears beside the zone name in the Association section. Clicking on this hyperlink disassociates the segment from the zone in question. Once a segment is disassociated from a zone, the components that are part of the segment will also be disassociated from the zone. If "automatic association" has been enabled for the zone, then the services (if any) that include the disassociated segment will also be removed from the zone, automatically. On the contrary, if "automatic association" is disabled, only the disassociated segments and components within will be removed from the zone, and not the related services.

Note:

• All the components that are not a part of any segment are considered as independent components.
• Once a segment is assigned to a service, then in the Association section of this page you will find a comma-separated list of services that are associated with that segment. To view/modify the service configuration directly from this page, click on the corresponding service name in the mapping. The Modify a Service page of that service will then appear.