如何在不先将PDF写入磁盘的情况下将PDF发送给Watson的Document Conversion服务? [英] How do I send a PDF to Watson's Document Conversion service without writing it to disk first?
问题描述
我正在尝试转换此文档(http://www.redbooks. ibm.com/redbooks/pdfs/ga195486.pdf)使用 watson-developer-cloud node.js库来回答Watson的文档转换服务中的单位.
I am trying to convert this document (http://www.redbooks.ibm.com/redbooks/pdfs/ga195486.pdf) to answer units in Watson's Document Conversion service using the watson-developer-cloud node.js library.
在实际程序(不是此测试程序)中，我正在检索文档并即时对其进行转换，而无需先将其写入磁盘.我之前在其他文档中已经做到了这一点，但是该库的最新版本(v 1.7.0 )似乎已更改，并且不再以我使用它的方式工作.但是，即使在我开始使用最新版本之前，该特定文档也无法转换.
In the actual program (not this test program), I am retrieving the document and converting it on-the-fly, without writing it to disk first. I have done this before with other documents, but the latest version of the library (v 1.7.0) seems to have changed and it no longer works the way I was using it. But even before I started using the latest version, this particular document would not convert.
我正在使用的带注释的测试代码如下.我尝试了几种方法来使其工作，下面的 var opts = { 您必须一次取消注释其中之一才能查看结果.
The annotated test code that I am using is below. I have tried several ways to get this to work, the variations of which are all commented out under var opts={ below. You have to uncomment one of them at a time to see the results.
'use strict';
var bluemix = require('./bluemix');
var extend=require('util')._extend;
var fs=require('fs');
var watson=require('watson-developer-cloud');
var streams = require('memory-streams');
var dcCredentials = extend({
url: '<url>',
version: 'v1',
username: '<username>',
password: '<password>'
}, bluemix.getServiceCreds('document_conversion')); // VCAP_SERVICES
var document_conversion = watson.document_conversion(dcCredentials);
var bookpdf=getBook('ga195486.pdf');
convert(bookpdf);
function getBook(filename)
{
var bl=fs.readFileSync(filename,'utf8');
return bl;
}
function convert(content)
{
var opts={ //uncomment ONE of these
// file: new Buffer(content), //See message #1 below
// file: {value: new Buffer(content), options: {}}, //see message #2 below
// file: {value: new Buffer(content), options: {contentType: "application/pdf"}}, //This used to work. See message #2 (again) below
// file: new streams.ReadableStream(content),//see message #3 below
conversion_target: "ANSWER_UNITS",
content_type:'application/pdf'
};
document_conversion.convert(opts,
function (err, response)
{
if (err)
{
console.log("Error converting doc: ", err);
}
else if (response.answer_units.length==0)
{
var msg="No answer units";
console.log(msg,response);
}
else
{
console.log('Works!');
console.dir(response);
}
}
);
}
//Message #1: This returns:
// No answer units { source_document_id: '',
// timestamp: '2016-05-23T16:18:23.825Z',
// media_type_detected: 'application/pdf',
// metadata: [],
// answer_units: [],
// warnings:
// [ { phase: 'pdf',
// warning_id: 'empty_input_to_converter',
// description: 'The input provided to the converter phase is empty or doesn\'t contain text that can be converted.' },
// { phase: 'normalized_html',
// warning_id: 'empty_input_to_converter',
// description: 'The input HTML document has no body content.' },
// { phase: 'answer_units',
// warning_id: 'empty_input_to_converter',
// description: 'The input provided to the converter phase is empty or doesn\'t contain text that can be converted.' } ] }
//Message #2: These return:
///home/david/git/ccb-contentbridge/node_modules/watson-developer-cloud/node_modules/request/node_modules/combined-stream/node_modules/delayed-stream/lib/delayed_stream.js:33
// source.on('error', function() {});
//
//TypeError: source.on is not a function
// at Function.DelayedStream.create (/home/david/git/ccb-contentbridge/node_modules/watson-developer-cloud/node_modules/request/node_modules/combined-stream/node_modules/delayed-stream/lib/delayed_stream.js:33:10)
// at FormData.CombinedStream.append (/home/david/git/ccb-contentbridge/node_modules/watson-developer-cloud/node_modules/request/node_modules/combined-stream/lib/combined_stream.js:43:37)
// at FormData.append (/home/david/git/ccb-contentbridge/node_modules/watson-developer-cloud/node_modules/request/node_modules/form-data/lib/form_data.js:68:3)
// at appendFormValue (/home/david/git/ccb-contentbridge/node_modules/watson-developer-cloud/node_modules/request/request.js:339:21)
// at Request.init (/home/david/git/ccb-contentbridge/node_modules/watson-developer-cloud/node_modules/request/request.js:352:11)
// at new Request (/home/david/git/ccb-contentbridge/node_modules/watson-developer-cloud/node_modules/request/request.js:142:8)
// at request (/home/david/git/ccb-contentbridge/node_modules/watson-developer-cloud/node_modules/request/index.js:55:10)
// at createRequest (/home/david/git/ccb-contentbridge/node_modules/watson-developer-cloud/lib/requestwrapper.js:134:10)
// at DocumentConversion.convert (/home/david/git/ccb-contentbridge/node_modules/watson-developer-cloud/services/document_conversion/v1.js:134:10)
// at convert (/home/david/git/ccb-contentbridge/testRedbooks.js:35:24)
//Message #3: This returns and then it hangs there:
//Error converting doc: { code: 400, error: 'Error in the web application' }
有人可以告诉我我做错了什么吗?
Can someone please tell me what I am doing wrong?
推荐答案
该特定文件大于文档转换服务当前可以处理的文件.不幸的是，我目前尚不清楚确切的极限值，但是团队意识到了这一点，并正在寻求改进.
That particular file is larger than what the Document Conversion service can currently handle. Unfortunately I don't have very good info on exactly what the limits are right now, but the team is aware of this and looking into making improvements.
如果您可以提供一个以前可以运行但与node.js库的v1.7.0兼容的示例，我将对其进行研究，并希望能够提供更好的信息.
If you can provide an example that worked previously but broke with the v1.7.0 of the node.js library, I'll take a look at that and hopefully be able to provide better info.
哦，在您的fs.readfileSync()通话中指定'utf8'可能会导致您遇到一些麻烦.
Oh, and specifying 'utf8' on your fs.readfileSync() call may be causing some of the trouble you're experiencing.
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