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Reuse Sessions

A session is the result of browsing on a website, and consists of the page, the page URL and the cookies and authentications obtained in the course. However, obtaining a session where the desired information is easily reached can require a number of navigation steps such as logging in.

If a robot is run frequently enough, and the response time needs to be very small, getting to a suitable session in the robot can require more time than is available. However, if the session is obtained once, and then shared between robots and robot runs, then great time savings is achieved.

Two steps are used for session reuse:

  1. The Save Session action: Saves a session in a variable.
  2. The Restore Session action: Restores a session from a variable.

Example

Assume that we have a robot that logs in to a website to collect and return data. However, the data that we seek to collect is distributed over many linked pages, such as with a next page link. We want the first invocation of the robot to log in to the site and return the data of the first page, and each subsequent invocation should then return a new chunk of data (the next page). We want to share the session of a logged-in user between robot invocations, but we also want to remember how much data we have returned. The robot could look something like the following example.

Reuse sessions

When the robot is called, it will first try to restore a session from an input variable. If one exists, that session is used and the next step clicks a next page link to get a fresh page of data. If no session is passed to the robot, the step fails, and the second alternative is executed, which does the logging in and also navigates to the relevant page on the site where the data may be found.

If the robot execution gets through one of the two alternative branches, it reaches the Save Session step. This saves the session to use the next time the robot is called. But for this to be possible, we need to return the session to the caller of the robot. This is handled by the Return Session step, which is a normal Return Value step that returns the value of a variable containing the session (the variable is of a type that has an attribute of attribute type Session in which our Save Session step stored the session). Finally, if the robot reaches the end of the data (no next page link exists on the page), then the Click Next set produces an error. This is ignored by the robot, because we set Error Handling to Skip Following Steps, but if we have a check mark in API exception, the caller would get an exception. For example, if the robot is called from Java, uses the check mark to know that the end of data has been reached.

After the session is saved, the remaining steps of the robot extract the data from the page, such as by looping over a table and returning a value for each row.

Note that in Design Studio, robot execution is not controlled by the natural flow of a robot run. It is controlled by the user interaction.

  1. To store the session, select the step following the Save Session step.

  2. Select the Restore Session action.