6.2. Top N

6.2. Top N
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The top N tab displays trend charts showing the top contributors to application transaction volume and how the top contributors vary over time. For example, you can view the top URIs for a specific host or all hosts.

This tab includes a control bar which allows you to select the host and service for which you would like to view top n trend data and the type of chart to display. You can also select a the specific time interval (see Chapter 10, Selecting a time period ), and filter on specific data (see Chapter 11, Filtering).

	Note
	When you have made changes to the selections for the chart, including creating a filter, you can save these selections in a bookmark (see Section 1.4, “Navigating around sFlowTrend-Pro using browser history and bookmarks”) so that you can easily return to the same chart at a later date.

6.2.1. HTTP top N charts

The following top n charts are available for understanding the top contributors to HTTP transaction volume.

Top methods
Top URIs
Top URI paths
Top URI files
Top URI extensions
Top URI hosts
Top URI paths
Top mime types
Top auth users
Top user agents
Top referrers
Top X-Forwarded-For
Top servers
Top clients
Top connections

6.2.2. Units

You can use the Units selector to choose the performance measurement used to calculate and display the top contributors. The following units are available:

Bytes/s: Calculates the top contributors based on the number of bytes/s in requests and responses.
Operations/s: Calculates the top contributors based on the number of operations per second.
Duration: Calculates the top contributors based on the mean duration of each transaction.

6.2.3. Understanding the Top N services chart

The legend in the Top N services chart shows the top contributors for the selected interval. The outlined time stamp, for example , on the x-axis indicates the currently selected interval. You can select an interval and see the top contributors in that interval by clicking with the left mouse button on the bar corresponding to the interval of interest. Each other bar in the chart will then be recolored so that it shows the transaction volume associated with the top contributors in the currently selected interval. This allows you to see how the top contributors change over time.

If the latest (right most) bar is selected and the Time setting is relative to now (for example Last hour see Chapter 10, Selecting a time period , the charts will be updated automatically and always display the contributors for the most recent minute.

The grey part of each bar represents transaction volume not attributable to the top N shown in the legend (ie it represents the contribution from other URIs, methods etc. that are not in the top N).

If the whole of a bar is grey, the transaction volume in its interval is not attributable to any of the top contributors in the currently selected interval. You can click on this bar to make it the currently selected interval and see its top contributors.

6.2.4. Displaying end host information

When Top servers, Top clients, or Top connections charts are displayed, you can find out more information about an end host by clicking on to the left of the host address in the legend. This will open the Lookup host dialog using the end host address. If the Lookup host dialog is already open, then the dialog will be changed to show information for the newly selected host. See Chapter 12, End host information for more information.

6.2.5. Using the legend to drill-down into service data

You can use the legend in the services top N charts to drill-down into the service data. For example, if you are viewing a Top URI hosts chart and you notice that most of the activity involves one URI host, you can investigate which URIs for this host are being accessed by clicking with the left mouse button on legend item that corresponds to the URI host. The Top URIs chart will then be displayed with a filter for the selected URI host applied.

See Chapter 11, Filtering for more information of filtering.

6.2.6. Filtering for specific data

sFlowTrend-Pro allows you to filter information displayed in a Top N services chart. This allows you to focus on data that may be of interest. For example, when viewing Top URIs, if you only wanted to look at URIs accessed with HTTP GET, you could set a filter httpMethod=="GET". See Chapter 11, Filtering for details.