deflate | 易学教程

Go unmarshalling JSON from compessed HTTP: invalid character looking for beginning of value

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问题 I've just written my first Go application which downloads and unmarshales simple JSON object over http. Http content is compressed: 'content-encoding': 'deflate' I used several well-known examples (like this). Unfortunately the application fails to parse the desired JSON with quite rare and strange error. I wasn't able to find out what's the problem. Any help will be appreciated. JSON input (Python was used for debugging) In [8]: r = requests.get("http://172.17.0.31:20000/top") In [9]: r.text

Implementing permessage-deflate in WebSockets

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问题 I hava a problem understanding and implementing a permessage-deflate extension in WebSockets. So far, I have added 'Sec-WebSocket-Extensions: permessage-deflate' inside handshake code. It seems to work all fine. However when I send a "TEST" message from the server (Node.js) to the Client (JS), it seems that the browser (both Chrome and Firefox) is not decompressing the data itself. How to properly implement data compression and decompression using permessage-deflate extension? Request Header:

【整理】HTTP 协议中的压缩问题

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公司因业务需要，要求实现 REST API 的 HTTP 客户端支持 gzip 压缩。那么首先需要回答下面几个问题： gzip 压缩和其他压缩方式有什么不同？或者说优劣在哪里？ HTTP 协议中对压缩方式的常规支持有哪些？ =========== 我是分割线 ============ 查阅相关资料如下： LZ77 是一种基于字典的无损数据压缩算法（还有 LZ78, LZW 等）。 deflate 是一种数据压缩算法，实际上就是先用 LZ77 压缩，然后用霍夫曼编码压缩。 gzip 的基础是 defalte 。其通过 defalte 算法压缩数据，然后加上 gzip 文件头和 CRC 校验。压缩后生成 .tar.gz 或者 .tgz 文件。既是一种文件结构，也可以算一种压缩格式。 ZIP 也使用 defalte 算法，但可移植性更好，并且不需要一个外部的归档工具就可以包容多个文件。但是由于 ZIP 对每个文件进行单独压缩而没有利用文件间的冗余信息(固实压缩)，所以 ZIP 的压缩率要稍逊于 tar 压缩包。 zlib 是一个提供了 deflate, zlib, gzip 压缩方法的函数库；同时也是一种压缩格式，可以通过 deflate 压缩数据，之后加上 zlib 头和 CRC 校验来生成 zlib 文件格式。 bzip2 是一个基于数据块排序算法的文件压缩工具，并作为

Web服务器处理HTTP压缩之gzip、deflate压缩

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一、什么是gzip gzip是一种数据格式，默认且目前仅使用deflate算法压缩data部分； Gzip是一种流行的文件压缩算法，现在的应用十分广泛，尤其是在Linux平台。当应用Gzip压缩到一个纯文本文件时，效果是非常明显的，大约可以减少70％以上的文件大小。这取决于文件中的内容。利用Apache中的Gzip模块，我们可以使用Gzip压缩算法来对Apache服务器发布的网页内容进行压缩后再传输到客户端浏览器。这样经过压缩后实际上降低了网络传输的字节数，最明显的好处就是可以加快网页加载的速度。网页加载速度加快的好处不言而喻，除了节省流量，改善用户的浏览体验外，另一个潜在的好处是Gzip与搜索引擎的抓取工具有着更好的关系。例如 Google就可以通过直接读取gzip文件来比普通手工抓取更快地检索网页。在Google网站管理员工具（Google Webmaster Tools）中你可以看到，sitemap.xml.gz 是直接作为Sitemap被提交的。而这些好处并不仅仅限于静态内容，PHP动态页面和其他动态生成的内容均可以通过使用Apache压缩模块压缩，加上其他的性能调整机制和相应的服务器端缓存规则，这可以大大提高网站的性能。因此，对于部署在Linux服务器上的PHP程序，在服务器支持的情况下，我们建议你开启使用Gzip Web压缩。 PS：详情参考： http:/

The structure of Deflate compressed block

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问题 I have troubles with understanding Deflate algorithm (RFC 1951). TL; DR How to parse Deflate compressed block 4be4 0200 ? I created a file with a letter and newline a\n in it, and run gzip a.txt . Resultant file a.txt.gz : 1f8b 0808 fe8b eb55 0003 612e 7478 7400 4be4 0200 07a1 eadd 0200 0000 I understand that first line is header with additional information, and last line is CRC32 plus size of input (RFC 1951). These two gives no trouble to me. But how do I interpret the compressed block

One library for deflate, gzip, and zlib in .net

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问题 First, let's define some commonly confused terms: deflate = compression_algorithm; zlib = header + deflate + trailer; gzip = header + deflate + trailer; I'm looking for a library that will basically let me do the following: if(method == "gzip"){ Response.Filter = new CompressionLibrary.OutputStream(Response.Filter, CompressionLibrary.Formats.GZIP); } else if(method == "deflate"){ Response.Filter = new CompressionLibrary.OutputStream(Response.Filter, CompressionLibrary.Formats.DEFLATE); } else

Reusing a data dictionary for 'Deflate' separate from the compressed data

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问题 I am storing many chunks of base64 encoded 64-bit doubles in an XML file. The double data all looks similar. The double data is currently being compressed using the java 'Deflate' algorithm before the encoding, however each chunk of binary data in the file will have its own deflate data dictionary, which is an overhead I would like to greatly lessen. The 'Deflater' class has a 'setDictionary' method which I would like to use. So questions are: 1). Does anyone have any suggestions for how to

Enable mod_deflate to send Content-Encoding: gzip

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问题 EDIT I have found that the problem is actually php minify. This was sending the deflated content instead of Apache. I'll find more on this. According to High Performance Web Sites, if I enable mod_deflate in Apache 2.x, by adding the following line, it should send gzipped/delfated content: - AddOutputFilterByType DEFLATE text/html text/css application/x-javascript The book also says that gzip is more effective than deflate . I have enabled in httpd.conf by adding the same line. But Apache

How to compress data on asp.net and uncompress in javascript

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Hi this is my first Question :) I need a lib or way to compress a data in asp.net (vb) with the algorit deflate but the result inflate in javascript. I'm use a lib in javascript: deflate.js hxxp://www.codeproject.com/KB/scripting/Javascript_binaryenc.aspx?msg=2904739 First i'm deflate and convert to base64 the result but the result is no compatible with the javascript lib. i'm use the Chilkat .NET DLL hxxp://www.example-code.com/vbdotnet/deflate_string.asp The String result with this lib is compatible with the javascript libray but is not free. I need a way to compress data in asp.net and

Decompress file from Boost filtering_streambuf to std::vector<char>?

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I'm trying to decompress a file that was compressed using the DEFLATE algorithm and stuff it into a vector<unsigned char> . From the research I've done so far, it seemed like I could use a boost::iostreams::filtering_streambuf and then use boost::iostreams::copy() to get it into a boost::interprocess::basic_vectorstream<std::vector<unsigned char>> and then pull the underlying vector out of the vectorstream. However, I'm getting a ton of compiler errors, starting with this: /usr/include/boost/iostreams/copy.hpp: In function ‘std::streamsize boost::iostreams::detail::copy_impl(Source, Sink, std:

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