I'm new to c++, I'm learning with the book "C++ Primer"(I am at page 710) but I'm trying to learn too how to use streams from cpprestsdk.
How can I use Concurrency::streams::async_istream and
Concurrency::streams::async_ostream to take a string from the console and output that stream to console?
I have googled a lot without luck. no one use cpprestsdk today for http request and Json?
The only web who gives Info is CppRestSdk Documentation and there isn't any example about anything, and [http://msdn.microsoft.com] who gives just 3 poor examples of streams, Json and http_requests.
If I'm very lost, please help me to improve my way to learn http_requests and Json in c++ giving me advices.
Thank you!
I'm a C++ programmer and I want to write an application purely in C++ and HTML5 and CSS without any knowledge of JavaScript with the help of Portable Native Client. I am not intended to learn JavaScript either. Is this possible?
The only way for NaCl/PNaCl C/C++ to effect the DOM is by passing messages to JavaScript (using postMessage()) and having JavaScript perform the DOM actions required.
The only way for C/C++ to render directly is to use the 2D or 3D canvas APIs.
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I have been writing some codes to get some data from some pages in Java and Jsoup was on of the best libraries to work with. But, Unfortunately I have to port the whole code to C/C++. But I a cannot find any decent html parser to use on c++. Is there any Jsoup like library for C++ or How can similar results be achieved?
[Currently I am using Curl to get the source of the pages and roaming the internet to find a html parser]
Unfortunately, i guess there's no parser like Jsoup for C++ ...
Beside the libraries which are already mentioned here, there's a good overview about C++ (some C too) parser here: Free C or C++ XML Parser Libraries
For parsing i used TinyXML-2 for (Html-) DOM parsing; it's a very small (only 2 files) library that runs on most OS (even non-desktop).
LibXml
push and pull parser (DOM, SAX)
Validation
XPath and XPointer support
Cross-Plattform / good documentation
Apache Xerxces
push and pull parser (DOM, SAX)
Validation
No XPath support (but a package for this?)
Cross-Plattform / good documentation
If you are on C++ CLI, check out NSoup - a Jsoup port for .NET.
Some more:
htmlcxx - html and css APIs for C++
MSHTML (?)
pugixml (DOM / XPath and Unicode support)
LibCSS (CSS Parser) / LibDOM (DOM) (however, both in C)
hcxselect (CSS selector engine for C++)
Maybe you can combine a DOM Model / Parser and a CSS selector together?
If you are familiar with Qt Framework the most convenient way is using QWebElement (Reference here).
Otherwise, (as another post suggests) using Tidy to convert HTML to a valid XML and then using an XML parser such as libxml++ is a good option. You can find a sample code showing these two steps here.
Chromium has an open source parser. Also, the Google gumbo-parser looks cool.
Yes, there is a html parser lib for c++, check it out
https://github.com/HamedMasafi/HtmlParser/
This library can parse html or css and convert it to a tree model. You can search in parsed html by methods like: get_by_id, get_by_class_name, get_by_tag_name, and also there is a question method that you can search via css selector (only tag, id, class, nested childs selectors supported for now).
After finding a child you can change it's attributes and in final you can print a html into std::string in compact and pretty mode.
You can use xerces2 as DOM parser.
Or use HTML Tidy to clean up the HTML and convert it to XHTML then parse the XML with pugixml or similar XML parser. And since pugixml is a non-validating parser, it might as well work on the raw HTML without the need of runnin HTML Tidy on it first.
If you don't mind calling out to python from C++, you could use Beautiful Soup. At least the name is right!
Seriously - it's a nice, no-nonsense HTML parser. I haven't tried calling out to it from C++, although it should be straightforwards.
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How does one intelligently parse data returned by search results on a page?
For example, lets say that I would like to create a web service that searches for online books by parsing the search results of many book providers' websites. I could get the raw HTML data of the page, and do some regexs to make the data work for my web service, but if any of the websites change the formatting of the pages, my code breaks!
RSS is indeed a marvelous option, but many sites don't have an XML/JSON based search.
Are there any kits out there that help disseminate information on pages automatically? A crazy idea would be to have a fuzzy AI module recognize patterns on a search results page, and parse the results accordingly...
I've done some of this recently, and here are my experiences.
There are three basic approaches:
Regular Expressions.
Most flexible, easiest to use with loosely-structured info and changing formats.
Harder to do structural/tag analysis, but easier to do text matching.
Built in validation of data formatting.
Harder to maintain than others, because you have to write a regular expression for each pattern you want to use to extract/transform the document
Generally slower than 2 and 3.
Works well for lists of similarly-formatted items
A good regex development/testing tool and some sample pages will help. I've got good things to say about RegexBuddy here. Try their demo.
I've had the most success with this. The flexibility lets you work with nasty, brutish, in-the-wild HTML code.
Convert HTML to XHTML and use XML extraction tools. Clean up HTML, convert it to legal XHTML, and use XPath/XQuery/ X-whatever to query it as XML data.
Tools: TagSoup, HTMLTidy, etc
Quality of HTML-to-XHML conversion is VERY important, and highly variable.
Best solution if data you want is structured by the HTML layout and tags (data in HTML tables, lists, DIV/SPAN groups, etc)
Most suitable for getting link structures, nested tables, images, lists, and so forth
Should be faster than option 1, but slower than option 3.
Works well if content formatting changes/is variable, but document structure/layout does not.
If the data isn't structured by HTML tags, you're in trouble.
Can be used with option 1.
Parser generator (ANTLR, etc) -- create a grammar for parsing & analyzing the page.
I have not tried this because it was not suitable for my (messy) pages
Most suitable if HTML structure is highly structured, very constant, regular, and never changes.
Use this if there are easy-to-describe patterns in the document, but they don't involve HTML tags and involve recursion or complex behaviors
Does not require XHTML input
FASTEST throughput, generally
Big learning curve, but easier to maintain
I've tinkered with web harvest for option 2, but I find their syntax to be kind of weird. Mix of XML and some pseudo-Java scripting language. If you like Java, and like XML-style data extraction (XPath, XQuery) that might be the ticket for you.
Edit: if you use regular expressions, make sure you use a library with lazy quantifiers and capturing groups! PHP's older regex libraries lack these, and they're indispensable for matching data between open/close tags in HTML.
Without a fixed HTML structure to parse, I would hate to maintain regular expressions for finding data. You might have more luck parsing the HTML through a proper parser that builds the tree. Then select elements ... that would be more maintainable.
Obviously the best way is some XML output from the engine with a fixed markup that you can parse and validate. I would think that a HTML parsing library with some 'in the dark' probing of the produced tree would be simpler to maintain than regular expressions.
This way, you just have to check on <a href="blah" class="cache_link">... turning into <a href="blah" class="cache_result">... or whatever.
Bottom line, grepping specific elements with regexp would be grim. A better approach is to build a DOM like model of the page and look for 'anchors' to character data in the tags.
Or send an email to the site stating a case for a XML API ... you might get hired!
You don't say what language you're using. In Java land you can use TagSoup and XPath to help minimise the pain. There's an example from this blog (of course the XPath can get a lot more complicated as your needs dictate):
URL url = new URL("http://example.com");
SAXBuilder builder = new SAXBuilder("org.ccil.cowan.tagsoup.Parser"); // build a JDOM tree from a SAX stream provided by tagsoup
Document doc = builder.build(url);
JDOMXPath titlePath = new JDOMXPath("/h:html/h:head/h:title");
titlePath.addNamespace("h","http://www.w3.org/1999/xhtml");
String title = ((Element)titlePath.selectSingleNode(doc)).getText();
System.out.println("Title is "+title);
I'd recommend externalising the XPath expressions so you have some measure of protection if the site changes.
Here's an example XPath I'm definitely not using to screenscrape this site. No way, not me:
"//h:div[contains(#class,'question-summary')]/h:div[#class='summary']//h:h3"
You haven't mentioned which technology stack you're using. If you're parsing HTML, I'd use a parsing library:
Beautiful Soup (Python)
HTML Agility Pack (.NET)
There are also webservices that do exactly what you're saying - commercial and free. They scrape sites and offer webservice interfaces.
And a generic webservice that offers some screen scraping is Yahoo Pipes. previous stackoverflow question on that
It isn't foolproof but you may want to look at a parser such as Beautiful Soup It won't magically find the same info if the layout changes but it's a lot easier then writing complex regular expressions. Note this is a python module.
Unfortunately 'scraping' is the most common solution, as you said attempting to parse HTML from websites. You could detect structural changes to the page and flag an alert for you to fix, so a change at their end doesn't result in bum data. Until the semantic web is a reality, that's pretty much the only way to guarantee a large dataset.
Alternatively you can stick to small datasets provided by APIs. Yahoo are working very hard to provide searchable data through APIs (see YDN), I think the Amazon API opens up a lot of book data, etc etc.
Hope that helps a little bit!
EDIT: And if you're using PHP I'd recommend SimpleHTMLDOM
Have you looked into using a html manipulation library? Ruby has some pretty nice ones. eg hpricot
With a good library you could specify the parts of the page you want using CSS selectors or xpath. These would be a good deal more robust than using regexps.
Example from hpricot wiki:
doc = Hpricot(open("qwantz.html"))
(doc/'div img[#src^="http://www.qwantz.com/comics/"]')
#=> Elements[...]
I am sure you could find a library that does similar things in .NET or Python, etc.
Try googling for screen scraping + the language you prefer.
I know several options for python, you may find the equivalent for your preferred language:
Beatiful Soup
mechanize: similar to perl WWW:Mechanize. Gives you a browser like object to ineract with web pages
lxml: python binding to libwww
scrapemark: uses templates to scrape pieces of pages
pyquery: allows you to make jQuery queries in xml/xhtml documents
scrapy: an high level scraping and web crawling framework for writing spiders to crawl and parse web pages
Depending on the website to scrape you may need to use one or more of the approaches above.
If you can use something like Tag Soup, that'd be a place to start. Then you could treat the page like an XML API, kinda.
It has a Java and C++ implementation, might work!
Parsley at http://www.parselets.com looks pretty slick.
It lets you define 'parslets' using JSON what you're define what to look for on the page, and it then parses that data out for you.
As others have said, you can use an HTML parser that builds a DOM representation and query it with XPath/XQuery. I found a very interesting article here: Java theory and practice: Screen-scraping with XQuery - http://www.ibm.com/developerworks/xml/library/j-jtp03225.html
There is a very interesting online service for parsing websites https://loadsiteinmysql.site This service splits the site into tags and loads them into MySQL tables. This allows you to parse sites using MySQL syntax
I have worked with SOAP in SAAJ and JAXM, and I want to extend on that, and throw in some WSDL and UDDI.
What was, for you, the most useful book or article when you learned WSDL? What tools came in handy when trying to create and run some examples?
Thank you.
I am answering my own question since I did not get a lot of responses.
I eventually found a good article and used it as a basis for beginning to learn WSDL. I extended on it by reading other articles similar to the one specified by adatapost or by google-ing. For specific details I turned to the specifications as John Saunders suggested.
This is the material that I found most useful when starting to learn WSDL: Understanding WSDL. Hope it helps somebody else too.
Web Services Description Language (WSDL) 1.1
but also
WS-I Basic Profile Version 1.1 to learn what parts of WSDL to not use.