Friday, 29 July 2011

Web View Experiences - View Sizes

Our GUI client design for list boxes is to retrieve all of the rows that satisfy the filter criteria and then allow the user to easily scroll up and down through the list box. Because of the 32k view size limit on the server procedure step, the client list box size is much larger than the server view size. For example, the client list box might allow up to 32000 rows (the limit for a GUI list box is 32767 rows) but the server group view size might be 100 rows, so the client would call the server multiple times to retrieve all of the data.

Whilst this approach works well for a GUI client, it presents performance problems for the web interface. Therefore our design for the web interface is to only call the server once to retrieve the first set of rows (for example 100) and then provide Prev and Next buttons on the web page to support paging.

The servers will already support the Next page operation because this would use a 'start from' field that would be set in the GUI client to page forward through the data. However our servers typically did not need to support a 'previous page' operation and so this has had to be added to the servers to support the web interface.

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