Viewing a Chart (Standalone View)

*USE CASE: Viewing a Chart (Standalone View)*

*Primary Actor: User

*Scope: XWiki

*Level: User goal

*Stakeholders and Interests:
User: Wants to view a single existing XWiki chart.
User Agent: Displays XWiki pages, in this case a page containing the requested chart.
Server: Serves chart requests made by the user agent.

*Precondition: The user has permission to view the requested chart.

*Minimal guarantees: The page contains a valid chart.

*Success guarantee: The server is able to process the chart and generate a graphical representation thereof, which will be sent to the user client.

*Main success scenario:
1.The user selects an XWiki page that contains a chart, either by following a link from another page, or by entering the right URL, having the form http://www.example.com/xwiki/bin/charts/path/chartName?xpage=view.
2.The user agent processes the user's action and forwards a page request to the server.
3.The server receives the request and generates a simple container page linking to the chart, using a mark-up language corresponding to the user agent (usually HTML)
4.The server sends the page back to the client agent.
5.The user agent will make one or more additional requests to the server asking for the chart image.
6.The server will generate the chart and send the image to the user agent.
6.1.The server fetches the data from the data source.
6.2.The server constructs an appropriate internal representation of the data.
6.3.The server generates an image representing the chart (e.g. SVG, PNG, etc.)
6.4.The server sends the image to the user.
7.The user agent presents the page containing the chart image to the user.

*Extensions:
6a. If caching is used then sometimes is enough to fetch the chart image from a cache.