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Problem: Limitations of Esri Maps for IBM Cognos and Internet Explorer

Description

This document describes limitations that may be encountered when using Internet Explorer (IE) to create or view map-enabled HTML reports in IBM Cognos. The document also provides a set of best practices to help mitigate these limitations.

Cause

IBM Cognos requires that HTML reports be rendered in a mode that is not compatible with certain mapping functionality. This mode, known as Quirks mode, can also negatively affect performance. Quirks mode is a technique that web browsers use to maintain backward compatibility with web pages designed for older browsers. As such, Quirks mode does not strictly comply with W3C and IETF standards.

In the context of IE, Quirks in versions 6, 7, 8 and 9 refers to a mode of rendering compatible with IE 5.5. As of IE 10, the primary Quirks mode is no longer an imitation of IE 5.5. Rather, it is designed to be interoperable with the Quirks modes of other browsers. IE 10 and 11, however, still have an IE 5.5-imitating Quirks mode. IBM Cognos requires that HTML reports be rendered in the IE 5.5-imitating Quirks mode, regardless of IE version.

IBM Cognos ensures the IE 5.5-imitating behavior by using an HTML <!DOCTYPE> declaration, and by requiring that IE display reports in compatibility view. IBM Cognos technote 16677330 indicates the need for compatibility view and provides instructions for configuring a web server with an X-UA-compatible HTTP header to ensure IE 5.5 Quirks behavior. Some HTML pages served by IBM Cognos achieve the same result by specifying an X-UA-compatible meta tag. To see the document rendering mode of any HTML page, use the developer tools in IE (accessed with the F12 key).

Limitations
Maps can be rendered and used within IE. However, because of the IE 5.5 rendering mode, some limitations and behaviors should be noted.

• Heat maps and pie chart clusters

Esri Maps for IBM Cognos renders heat maps and pie chart clusters using the HTML5 canvas object. Because this object does not exist in IE 5.5 Quirks mode, heat maps and pie chart clusters cannot be drawn.

• Performance

Features render more slowly in IE than in Firefox or Chrome. In some versions of IE, users experience 'Long-running script' messages. The main reason for this is the format used to render vector graphics. IE 5.5 Quirks mode uses Vector Markup Language (VML) which is a deprecated format as of IE 10. VML is only supported in IE 10 and 11 when the browser is set to a document mode that emulates the functionality of earlier versions of IE (IE 5.5 in this case). In IE 10 and later, Scalable Vector Graphics (SVG) have replaced the functionality provided by VML in earlier versions of IE. SVG provides significant improvements in graphic rendering capabilities as compared to VML.

The following chart shows rendering times for point features in IE 11. Datasets of 1000, 5000, 10000, and 25000 points were used in a generic web application (not IBM Cognos) so that different rendering modes could be used.

[O-Image]

Click here to see the results in table format:
[O-Image]
As can be seen, SVG rendering performs much better and is therefore more scalable. For this reason, IE is not recommended for working with datasets of more than 1000 features.

Solution or Workaround

The following best practices are recommended:

Use a browser other than IE. Refer to the ESRI Maps for IBM Cognos documentation for a list of supported browsers.

Author reports with a view to limiting the number of features to be drawn. In Esri Maps for IBM Cognos 6.0, map designers have the ability to view the feature layer’s attribute table for IBM Cognos data using View records. This tool is useful for troubleshooting the layer data and helping map authors understand what data is added to the map. By using this tool, map authors can work with IBM Cognos report authors to create efficient queries to improve map rendering. IBM Cognos report authors can add filters and prompts to IBM Cognos reports to limit the amount of data the browser has to render. The browser then has a smaller set of images and graphics to render, thereby reducing rendering time.

Disable IE notifications about script errors. See the Disable script debugging section of Microsoft document 308260.