In the 4.0 nightly community builds, extra log4j debug was added (code from 4.0.1 and 3.4.8 service packs) to track which content transformers have been used, which are available, why they have been selected and why they are not available.
The following section shows how to turn on debug and includes an example sequence of uploading a Microsoft Excel file and then previewing it in Share.
Turning on debug
This is achieved by adding the following log4j property.
DEBUG 1 xlsx png Small1.xlsx 12.7 KB ContentService.transform(...) DEBUG 1 **a) transformer.complex.OpenOffice.Image<Complex>> 0 ms DEBUG 1 b) transformer.complex.JodConverter.Image<Complex>> 0 ms DEBUG 1.1 xlsx pdf Small1.xlsx 12.7 KB transformer.OpenOffice<Proxy>> DEBUG 1.2 pdf png <TemporaryFile>> 16.1 KB transformer.complex.PDF.Image<Complex>> DEBUG 1.2.1 pdf png <TemporaryFile>> 16.1 KB transformer.PdfToImage<Failover>> DEBUG 126.96.36.199 pdf png <TemporaryFile>> 16.1 KB failover.transformer.PdfRenderer.PdfToImage DEBUG 1.2.2 png png <TemporaryFile>> 34.9 KB transformer.ImageMagick<Proxy>> DEBUG 1 Finished in 2,361 ms
Debug lines for each request are prefixed with the same number.
This request shows the creation of a png file for the thumbnail used to represent the Excel file in the Document Library.
As can be seen, this uses a complex transformer, which means it is composed of lower level transformers.
In this case the xlsx (Excel extension) is converted to pdf (1.1) then to a png (1.2).
This example looks a little strange as the png created in 1.2.1 (by 188.8.131.52) is then transformed into another png in 1.2.2 which turns it into a thumbnail.
Each nested transformer is given a nested number.
The name of the source file (Small1.xlsx) to each transformer is included. Were an intermediate file is used there is no name and <TemporaryFile>> appears.
Don't worry too much about all the detail yet.
Indexer checks to see if it should run on upload
DEBUG 2 xlsx txt Small1-1.xlsx 12.7 KB ADMLuceneIndexer DEBUG 2 **a) transformer.Poi 58 ms DEBUG 2 Run later. Transformer average (58 ms) > 20 ms DEBUG 2 Finished in 2 ms Transformer NOT called
The Indexer makes a check to see if it is worth converting the xlsx to text at this stage.
As can be seen, it does not do so, as the average transformation time is 58 ms which is above the 20 ms threshold.
As a result file will get indexed later in an background thread.
Indexer does not index the thumbnail
DEBUG 3 png txt doclib 10.2 KB ADMLuceneIndexer NO transformers DEBUG 3 Finished in 2 ms Transformer NOT called
The Indexer now checks to see if it can index the png file that was just created.
It does not attempt to transform the png as there are no transformers that can do this as shown on line 2.
In this case the name (such as doclib or preview) indicates the class of thumbnail.
Indexer runs in background
DEBUG 4 xlsx txt Small1.xlsx 12.7 KB ADMLuceneIndexer DEBUG 4 **a) transformer.Poi 58 ms DEBUG 4 Finished in 64 ms
The Indexer now transforms the xlsx file to text so that it may add it to the index. This is taking place in a background thread.
DEBUG 5 xlsx swf Small1.xlsx 12.7 KB ContentService.transform(...) DEBUG 5 **a) transformer.complex.JodConverter.Pdf2swf<Complex>> 0 ms DEBUG 5 b) transformer.complex.OpenOffice.Pdf2swf<Complex>> 0 ms DEBUG 5.1 xlsx pdf Small1.xlsx 12.7 KB transformer.JodConverter<Proxy>> DEBUG 5.2 pdf swf <TemporaryFile>> 16.1 KB transformer.Pdf2swf<Proxy>> DEBUG 5 Finished in 916 ms
Moving to the preview page, the xlsx needs to be transformed into the mimetype 'application/x-shockwave-flash' (extension swf).
Again this requires a complex transformer. In this case there are two, one called ' 'transformer.complex.JodConverter.Pdf2swf' and the other is called 'transformer.complex.OpenOffice.Pdf2swf'.
The '0 ms' value after the transformer name is the average time it has taken to transform content in the past. In this case neither have been used before.
The '**' indicates which one is going to be used. The one with the lowest value is used.
As the swf file is stored, you will not see this transformation take place again.
You can also see the size of the xlsx file (12.7 KB) and the intermediate pdf file (16.1 KB) are shown. This is useful when setting up limits on transformations.
You may have spotted that the second line indicates where the request is coming from. In this case a public API ContentService.transform(...), which converts a file.
Indexer does not index the preview
DEBUG 6 swf txt preview 87.9 KB ADMLuceneIndexer NO transformers DEBUG 6 Finished in 2 ms Transformer NOT called
The Indexer then checks to see if it can index the swf file just created, in the same way it did for the png in request 3.
To gain a little more background context to the transformations, you may wish to turn on some more log4j output. The following Content Audit trace shows high level operations on nodes performed by the user. The following example shows the upload and the preview of the file Small1.xlsx.
When a transformer is not selected because of a source size limit, this is reflected in the output with a '--' prefix. This example shows a transformation request from txt to png. However in this case, transformer.PdfToImage is not able to handle source files larger than 1 MB, because it would be too slow or it is known that another transformer is faster or better for another reason.
Also note the 'Page limit (1) reached. Returning EOF' log message indicating that another limit has been applied. In this case only one page of pdf has been generated as there is no need to create more when generating a png thumbnail for the Document Library.
Turning on trace
More information is available if the TransformerDebug logging level is set to TRACE rather than DEBUG.
TRACE 8 store://2012/2/13/14/2/8ec08fe3-8690-4f6f-9d1f-2aef176a63d7.bin TRACE 8 application/vnd.openxmlformats-officedocument.spreadsheetml.sheet application/x-shockwave-flash DEBUG 8 xlsx swf Small1.xlsx 12.7 KB ContentService.transform(...) DEBUG 8 **a) transformer.complex.OpenOffice.Pdf2swf<Complex>> 0 ms DEBUG 8 --b) transformer.not.enabled<Complex>> > 0 bytes TRACE 8.1 application/vnd.openxmlformats-officedocument.spreadsheetml.sheet application/pdf DEBUG 8.1 xlsx pdf Small1.xlsx 12.7 KB transformer.OpenOffice<Proxy>> TRACE 8.1 Finished in 502 ms TRACE 8.2 store://D:\workspaces\V4.0.0\apache-tomcat-6.0.29\temp\Alfresco\ComplextTransformer_intermediate_xlsx_2713205269292030258.pdf TRACE 8.2 application/pdf application/x-shockwave-flash DEBUG 8.2 pdf swf <TemporaryFile>> 8.1 KB transformer.Pdf2swf<Proxy>> TRACE 8.2 Finished in 199 ms DEBUG 8 Finished in 720 ms
The full source and target mimetypes (including intermediate stages), which is useful when configuring new transformations or limits on transformations.
The time taken to finish each sub transformer.
Transformers that have a limit of 0 bytes for a given mimetype. In other words they have been turned off.
TRACE 9 application/vnd.openxmlformats-officedocument.spreadsheetml.sheet image/png TRACE 9 xlsx png ContentService.getMaxSourceSizeBytes() = 1 MB TRACE 9 **a) transformer.complex.OpenOffice.Image<Complex>> 2,275 ms TRACE 9 Finished in 3 ms Transformer NOT called
TRACE 10 application/vnd.openxmlformats-officedocument.spreadsheetml.sheet application/x-shockwave-flash TRACE 10 xlsx swf ContentService.getMaxSourceSizeBytes() = 1 MB TRACE 10 **a) transformer.complex.OpenOffice.Pdf2swf<Complex>> 0 ms TRACE 10 Finished in 7 ms Transformer NOT called
TRACE 11 application/vnd.openxmlformats-officedocument.spreadsheetml.sheet image/jpeg TRACE 11 xlsx jpg ContentService.getMaxSourceSizeBytes() = 1 MB TRACE 11 **a) transformer.complex.OpenOffice.Image<Complex>> 2,275 ms TRACE 11 Finished in 6 ms Transformer NOT called
There will also be extra requests to the ContentService that have not resulted in a transformation taking place. For example, when the first file of a given mimetype is previewed in Share, the trace will show all the transformers that are available when creating various thumbnails. You will note there is call from ContentService.getMaxSourceSizeBytes() for each type of thumbnail. The call is setting up a cache and includes a maximum size that may be converted. This trace includes no filename or size, as the caller is gathering general information.
Trace extra calls to getTransformer
TRACE 12 store://2012/2/13/14/2/8ec08fe3-8690-4f6f-9d1f-2aef176a63d7.bin TRACE 12 application/vnd.openxmlformats-officedocument.spreadsheetml.sheet application/x-shockwave-flash TRACE 12 xlsx swf Small1.xlsx 12.7 KB ContentService.getTransformer(...) TRACE 12 **a) transformer.complex.OpenOffice.Pdf2swf<Complex>> 0 ms TRACE 12 Finished in 3 ms Transformer NOT called
TRACE 13 store://2012/2/13/14/2/8ec08fe3-8690-4f6f-9d1f-2aef176a63d7.bin TRACE 13 application/vnd.openxmlformats-officedocument.spreadsheetml.sheet application/x-shockwave-flash TRACE 13 xlsx swf Small1.xlsx 12.7 KB ContentService.getTransformer(...) TRACE 13 **a) transformer.complex.OpenOffice.Pdf2swf<Complex>> 0 ms TRACE 13 Finished in 5 ms Transformer NOT called
With trace turned on you will see extra requests not normally shown that are made to work out if it is possible to transform content before actually making the request. In the example above there are two such calls before the actual transform.
Sometimes it is useful to discover all the active transformers in the system, which transformations they support, any size limits they might have, how long they have taken on average and if there are any other transformers that have declared the same combination of mimetypes as an explicit transformation. Explicit transformations are used in preference to all other transformers that are not explicit.
This debug is produced when a file called debugTransformers.txt that contains 18 bytes exactly is uploaded to Share. This is to avoid the debug being generated accidentally. When done, all active and inactive transformers are listed. The debug is normally almost a couple of thousand lines long. The following is a small snippet.
DEBUG 15 Active and inactive transformers (list not reduced by 'explicit' settings) DEBUG 15.1 transformer.ImageMagick<Proxy>> 107 ms DEBUG 15.1 1) eps eps unlimited DEBUG 15.1 2) eps jp2 unlimited DEBUG 15.1 3) eps cgm unlimited . . . DEBUG 15.1 361) dwt dwt unlimited DEBUG 15.2 failover.transformer.PdfRenderer.PdfToImage 324 ms DEBUG 15.2 1) pdf png unlimited DEBUG 15.3 failover.transformer.PdfBox.PdfToImage 0 ms DEBUG 15.3 1) pdf png unlimited . . . DEBUG 15.6 transformer.PdfBox 0 ms DEBUG 15.6 1) pdf txt unlimited EXPLICIT DEBUG 15.6 2) pdf html unlimited DEBUG 15.6 3) pdf xhtml unlimited DEBUG 15.6 4) pdf xml unlimited . . . DEBUG 15.10 transformer.complex.OpenOffice.Image<Complex>> 3,400 ms DEBUG 15.10 1) txt eps 1 MB DEBUG 15.10 2) txt jp2 1 MB DEBUG 15.10 3) txt cgm 1 MB DEBUG 15.10 4) txt gif 1 MB . . . DEBUG 15.31 transformer.complex.JodConverter.Pdf2swf<Complex>> 0 ms INACTIVE DEBUG 15 Finished in 2,026 ms Transformer NOT called