Troubleshooting Language Resources

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Note

Indexing Service is no longer supported as of Windows XP and is unavailable for use as of Windows 8. Instead, use Windows Search for client side search and Microsoft Search Server Express for server side search.

 

This section contains tips and suggestions to help you validate your IStemmer and IWordBreaker implementations and ensure that they meet the requirements for Indexing Service.

General Recommendations

  • Ensure that the threading model for language resources is set to "both" in the registry.
  • Where possible, put language data in a resource in your DLL rather than in a separate file. This makes the DLL easier to install and make secure. Additionally, putting language data in a resource will result in improved performance for that language resource component.
  • Minimize the system resources that language resource components use. For example, if each instance of a language resource objects needs read-only access to a lexicon, consider sharing the lexicon across all instances.
  • Consider using the neutral word breaker to handle text that is not in the language or locale for your word breaker implementation. This will help ensure that text is processed consistently across all languages. The Word Breaker and Stemmer Sample provides a sample implementation of a language neutral word breaker.
  • Check all return codes and return them from functions like GenerateWordForms and BreakText. If indexing fails it is important to pass the error so the user is notified as to which documents were indexed.

Testing Stemmer Consistency

It is recommended that you monitor the performance of an IStemmer implementation for consistency under the following conditions:

  • The stemmer performs consistently across multiple calls to its Init method. The stemmer reinitializes with the same parameters as in the previous initialization, without releasing the parameters.
  • Given the same test corpus, and repetitions of the same query, the GenerateWordForms method produces the identical output and makes identical calls to the methods of the WordFormSink object.

Testing for Invalid Input in the Stemmer

It is recommended that you monitor how the IStemmer methods handle all errors related to invalid parameters. In addition, it is recommended that you ensure that the stemmer methods do not raise nonhandled exceptions. The stemmer should handle the following errors:

  • Call to the Init method with pfLicense set to NULL. Init fails and does not result in an access violation.
  • Call to the GetLicenseToUse method with the **ppwcsLicense parameter set to NULL. GetLicenseToUse does not result in an access violation.
  • Call to the GenerateWordForms method with the pwcInBuf set to NULL. GenerateWordForms fails (return E_FAIL) and does not result in an access violation.
  • Call to the GenerateWordForms method with the cwc equal to 0. GenerateWordForms returns successfully (return S_OK) and does not result in an access violation.
  • Call to the GenerateWordForms method with the pwcInBuf set to NULL and the cwc equal to 0. GenerateWordForms fails (return E_FAIL) and does not result in an access violation.

Testing Word Breaker Consistency

It is recommended that you ensure that the IWordBreaker implementation performs consistently under the following conditions:

  • Word breaker performs consistently across multiple calls to its Init method. The word breaker reinitializes with the same parameters as in the previous initialization, without releasing the parameters.
  • Given the same test corpus, and repetitions of the same query, the IWordBreaker::BreakText method produces the identical output and makes identical calls to the methods of the WordSink and PhraseSink objects.

Testing for Invalid Input in the Word Breaker

It is recommended that you ensure that the IWordBreaker methods handle all errors related to invalid parameters. In addition, it is recommended that you ensure that the word breaker methods do not raise nonhandled exceptions. The word breaker should perform the following functions and handle the following errors:

  • Call to IWordBreaker::Init must return either LANGUAGE_E_DATABASE_NOT_FOUND or S_OK.
  • Call toIWordBreaker::Init successfully initializes the *pfLicense parameter to FALSE and calls GetLicenseToUse. GetLicenseToUse does not result in an access violation.
  • Word breaker does not read past the end of the awcBuffer parameter in the IWordBreaker::BreakText method.
  • Call to the BreakText method with the pwcInBuf set to NULL. BreakText fails (return E_FAIL) and does not result in an access violation.
  • Call to the BreakText method with the cwc equal to 0. BreakText returns successfully (return S_OK) and does not result in an access violation.
  • Call to the BreakText method with the pwcInBuf set to NULL and the cwc equal to 0. BreakText fails (return E_FAIL) and does not result in an access violation.
  • Phrases generated during index creation contain the same number of words.
  • Phrases are generated during index creation through successive calls to the PutWord and PutAltWord methods in the WordSink object. The word breaker uses only the PhraseSink object during query time.

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