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[gil::io] Compilation issue
by Christian Henning 04 Jul '17

04 Jul '17

Hi all, my metaprogramming zen is failing me and I like to ask for some help. Using gil's updated develop branch the following code creates a compilation error with Visual Studio 2015 Update 3. #include <boost/gil/extension/io/tiff_all.hpp> using namespace std; using namespace boost; using namespace gil; int main() { gray1_image_t img; write_view( "", view( img ), tiff_tag() ); return 0; } The compiler output is here: https://pastebin.com/raw/d1AB9QMz I think the error is in https://github.com/boostorg/gil/blob/develop/include/boost/gil/premultiply.… but I'm not sure what to do. Any help would be very helpful! Thanks, Christian

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[Beast] Review
by Artyom Beilis 03 Jul '17

03 Jul '17

Hello, This is my formal review of Boost Beast. > What is your evaluation of the design? Also the general design is solid provides generic API that does the job it defined. The most problematic issue with Beast is it total reliance on static polymorphism. This comes to sometimes very painful issues like: Having the object code duplicated for different variants HTTP/HTTPS code Having all the implementation in headers increasing compilation time Adding complexity to end user since he needs to propagate the templates to various places. Virtually all concepts could be done with classic interfaces and virtual functions. Using of static polymorphism does not provide there performance advantage but reduces code maintainability and adds lots of headache to end user. Note: it does not contradict of using ASIO but lots of stuff could be pimpled or hidden having only few forward declarations of the relevant classes. > What is your evaluation of the implementation? >From what I seen didn't find may flows besides thous mentioned before (content-length - that was fixed) and non-blocking sockets aren't covered by tests. However I didn't look too much since the code is quite hard to read being too template heavy. Second major issue is that it puts all the heavy work on end user providing tiny parsing messaging layer that to be honest is the simple part of HTTP handing. It significantly limits its usability to virtually void. > What is your evaluation of the documentation? Documentation is OK - similar to ASIO - I think more examples should be needed and tutorials regarding how to do common tasks. > What is your evaluation of the potential usefulness of the library? VERY limited. The library does too little to be useful for real development. I don't really see a real need for a library that could potentially be used to create CURL or could potentially be used to write web framework that users will work over them. As a user of this library you need to deal with: - User has to have deep knowledge of HTTP protocol itself and be highly aware of various security related problems on WWW. - Protocol itself and know it up to the small details, timeouts and much more. - Being able to parse all parameters passed from getting query string, parsing multipart/form-data (a.k.a. file upload format) parse percent encoding, cookies. I suggest to drawing the line at some point when library becomes useful for somebody who for examples needs to implement RESTful service or send some post data to a form. The separation line that was drawn does not suite the needs of too many of potential users. I understand it is huge task to do but if first lines in your FAQ and many other talk about what the library doesn't do than probably something goes wrong. And please note I don't talk about sessions, url mapping, but much more basic stuff like multipart parsing, url-encoding. URL parsing, > Did you try to use the library? With which compiler(s)? Did you have any problems? Tried to compile several examples no problem. > How much effort did you put into your evaluation? A glance? A quick > reading? In-depth study? At least 10-12 hours of reading documentation, code, running some examples. Notifying potential problems. > Are you knowledgeable about the problem domain? Yes, I'm myself an author of CppCMS C++ Web Framework - fully featured web development platform for C++ that works in both synchronous and asynchronous modes, I implemented HTTP and FastCGI protocols, networking engines myself. Designed high performance services and more. > Should the library be included to Boost? Unfortunately NO. Two major reasons: - Abuse of static polymorphism where classing object oriented design with virtual functions can do better job. - The scope of the library is way too limited that it brings the question of its usability for real users. I fully acknowledge the huge high quality work the author did - something that kept me reviewing the library and providing the comments, but the library as it is today IMHO doesn't suit Boost Best Regards and Good Luck, Artyom Beilis

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[Beast] HTTP/1.0 Protocol compatibility
by Artyom Beilis 03 Jul '17

03 Jul '17

I can't find there an (sami)automatic way to manage HTTP/1.0 vs HTTP/1.1 compatibility? Example I have a client that supports HTTP/1.0 only and I need to transfer an unknown amount of data. Now as one who writes the server I need to check the clients protocol and choose chucked transfer encoding with possibility to keep connection keep alive or close one after data transfer using socket shutdown. Shouldn't this kind of stuff should be handled automatically or sami-automatically? Keep alive semantics between HTTP/1.0 and HTTP/1.1 is tricky and it is very easy to make a mistake. Also note I tested some of your examples and found that they responding with HTTP/1.1 on HTTP/1.0 requests. Artyom

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[property_tree] Is Boost.Property_tree maintaner active?
by Александр Зайцев 03 Jul '17

03 Jul '17

Hello. I see on Boost.Property_tree's Github repo a lot of PR. And I want to know, is maintainer active or not.

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[beast] Asynchronous examples
by Phil Endecott 03 Jul '17

03 Jul '17

Hi, Do any of the Beast examples show its use in asynchronous mode? I'm wondering how difficult it is to achieve this: future< vector< byte > > data = download(url); Regards, Phil.

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[beast] thread per connection example?
by Peter Dimov 02 Jul '17

02 Jul '17

Suppose that I want to implement an HTTP server that uses the thread per connection model. What example should I use as a starting point?

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[beast] Wy does message<> store Body::value_type?
by Peter Dimov 02 Jul '17

02 Jul '17

Why does message<isRequest, Body, Fields> store Body::value_type, using Body::reader and Body::writer to manipulate it, instead of the more straightforward approach of storing Body, which would have allowed making `get` and `put` members of the Body directly, instead of using intermediate classes?

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[beast] Automatic content-length?
by Peter Dimov 02 Jul '17

02 Jul '17

In this code, extracted from one of the examples in the documentation, // Set up the response, starting with the common fields response<string_body> res; res.version = 11; res.set(field::server, "test"); /*...*/ // We return responses indicating an error if // we do not recognize the request method. res.result(status::bad_request); res.set(field::content_type, "text/plain"); res.body = "Invalid request-method '" + req.method_string().to_string() + "'"; // Send the response write(stream, res, ec); field::content_length isn't set. Will Beast insert Content-Length based on the body size, or will it send the response with the field missing? The reason I ask is that I foresee forgetting the content_length to be a common mistake, and an asymptomatic one.

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[beast] socket versus stream
by Bjorn Reese 02 Jul '17

02 Jul '17

The HTTP API provides a set of free function for all operations, so all interaction follows this pattern: operation(socket, args); The WebSocket API wraps an Asio socket in a stream, so all operations are like this: stream.operation(args); I realize that the latter choice is a consequence of using SSL, but I am wondering why there is no socket.operation(args) style for the former?

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[gil::io] Dependent Name issue with VS2015 Update3
by Christian Henning 01 Jul '17

01 Jul '17

Hi all, using the new gil::io on gil's develop branch I get a compilation error with Visual Studio 2015 Update 3. When trying to read a tiff image: #include <string> #include <boost\gil\gil_all.hpp> #include <boost\gil\extension\io\tiff_all.hpp> using namespace std; using namespace boost::gil; int main() { rgba8_image_t img; read_image( string(), img, tiff_tag() ); return 0; } I get an error: error C2951: template declarations are only permitted at global, namespace, or class scope The problem seems to be with https://github.com/boostorg/gil/blob/develop/include/boost/gil/extension/io… Can someone please tell me if my issue is a compiler issue or simply a syntax error. Thanks, Christian

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