The Sad State Of HAR File Compatibility in 2013

calendarJune 24, 2013 in HttpWatch

Ok, that title is a bit misleading. There are lots of tools successfully using and exchanging HAR files. It should probably read the ‘Sad State of HAR File Compatibility with HttpWatch in 2013′.

Here are some attempts to import HAR files from other popular tools into HttpWatch for Windows:Chrome HAR Error

and in the HttpWatch iPhone app:

Firebug HAR Error

HttpWatch was one of the original adopters of the HAR file format and the first Windows GUI application that could open and display HAR files. During the implementation of the HAR import feature we were concerned about supporting variations in HAR files from other tools.

To address this problem we decided that we would validate HAR files against the spec during import and flag up anything that did not conform. The theory was that this would avoid users being confused by data not being displayed as they expected in files that had questionable content.

This worked well back in 2009 when we added HAR import. However, since then HAR version 1.2 has been released and it seems that many tools have drifted away from strictly following the HAR spec.

So what’s the best way to fix this situation? Here are some ideas:

  1. Make HttpWatch less picky about HAR files and don’t worry about inconsistencies
  2. Update the HAR file spec to make it have less constraints and provide hints about how HAR viewers should cope
  3. Have a publicly available HAR file validator in the same style of the W3C markup validation service
  4. Submit HAR file related bug reports to the popular HAR adopters to get any issues fixed

Please let us know if you have any thoughts on this. Perhaps, a combination of all four approaches would be best.

You can use the HAR validation built into HttpWatch for free against your own HAR files by downloading one the following:

If you attempt to open a HAR file an error message will be displayed if any incompatibility with the spec is detected.


HttpWatch Version 6.2 Supports Data Exchange with Firebug

calendarOctober 19, 2009 in Firefox , HttpWatch

We’ve been working with Jan Odvarko, from the Firebug team to create an open file format for sharing HTTP log files. It uses text based, JSON encoding and has been designed for ease of use over performance or comprehensiveness. Most popular programming languages have libraries that can handle the parsing or creation of JSON files so it should be relatively easy to extract data from or create HTTP ARchive (HAR) files.

We released HttpWatch version 6.2 today and one of its major new features is import:

Import of HAR file into HttpWatch Studio

and export of HAR files:

Export to HAR from HttpWatch

There’s no automation support and you can’t save a HAR file as a native HttpWatch log file in this version, but that will be added in a future update to HttpWatch.

To export files from the Net Panel Firebug you’ll need:

There’s also a HAR viewer that renders the file in your browser. At the moment, only Firebug and HttpWatch officially support this file format but other tools vendors are expected to add support in the near future.

The current version of the HAR file format is not as comprehensive as the native HttpWatch file format, so it is still worth saving your log files initially in the .hwl file format. You can then create HAR files if required in HttpWatch Studio.

HttpWatch version 6.2 also contains these new features:

  • A reload dialog is displayed in HttpWatch Studio if a log file has been externally modified
  • The Firefox plug-in now has the same cookie related functionality as the IE plug-in
  • ‘Open’ and ‘Open in New Tab’ commands have been added to the URL column’s context menu

A detailed list of changes and fixes in this release is available on the version history page .

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