Proof of Concept - Working with Remote PDF Data

I’m not sure how useful this will be to others, but it was an interesting question from a reader so I thought I’d share the result. Michael works with a remote service that returns PDF data as base64 encoded text. He wanted to know if it was possible to add a watermark to the PDF before serving it to the user. Here’s what I came up with.

First, I create a simple service that would read in a PDF file and return it as base64. This would fake the remote service Michael was working with. Note - this code was written "just to work", in a real application I'd add some caching to reduce the amount of file i/o.

component { remote string function getpdf() returnformat="plain" { var pdffile = "c:\users\raymond\desktop\the test.pdf"; var bits = fileReadBinary(pdffile); return toBase64(bits); } }

Ok, so how do we use this as a consumer and work with the bits. First, we write code to get the data from the service.

<!--- get my pdf from the 'remote' server ---> <cfhttp url="http://localhost/test.cfc?method=getpdf"> <cfset pdfdata = cfhttp.filecontent>

Just to be super anal here and make sure it's clear - no - you would never cfhttp to a local server. Again - I'm just trying to replicate Michael's environment.

Once you have the bits, how do you work with it? ColdFusion let's you manipulate PDF data very easily, but, it must start from one of two sources - either a real file (which doesn't necessarily need to be a PDF, Office docs work too) or the result of a cfdocument call. We have the data, but ColdFusion isn't going to be able to use it as is. So - we must save the file.

<cfset binary = toBinary(pdfdata)> <cfset tmpFile = getTempFile(getTempDirectory(),"pdf")> <cfset fileWrite(tmpFile, binary)>

Now, at this point, if we don't care about keeping a clean original, we can just manipulate it as is.

<cfpdf source="#tmpFile#" action="addwatermark" text="Property of Raymond">

And then finally, serve it to the user:

<cfheader name="Content-disposition" value="attachment;filename=new.pdf" /> <cfcontent type="application/pdf" file="#tmpFile#" deletefile="no">

Note the use of filename in the cfheader tag. Even though my PDF had some temporary name, I can give it a nicer name before sending it over.

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About Raymond Camden

Raymond is a developer advocate. He focuses on JavaScript, serverless and enterprise cat demos. If you like this article, please consider visiting my Amazon Wishlist or donating via PayPal to show your support.

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