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https://github.com/alibaba/nginx-http-slice

Nginx module for serving a file in slices (reverse byte-range)
https://github.com/alibaba/nginx-http-slice

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Nginx module for serving a file in slices (reverse byte-range)

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README 

        
# Nginx HTTP Slice module



## Introduction 



This is a module that is distributed with

[tengine](http://tengine.taobao.org) which is a distribution of

[Nginx](http://nginx.org) that is used by the e-commerce/auction site

[Taobao.com](http://en.wikipedia.org/wiki/Taobao). This distribution

contains some modules that are new on the Nginx scene. The

`ngx_http_slice_module` module is one of them.



This module can be thought out as a *reverse byte-range* request

header. It's main utility is to allow Nginx to slice a big file in

small pieces (byte-ranges) while permitting to use on-the-fly gzip

compression.



A typical example is for allowing someone to download a large video

file while keeping the bandwith usage minimal. This might also be used

as device for selling a video file by pieces where each link points to

different zones of the file splitted by file ranges.



Other use would be to use a generic CSS file and use only part of it

for each section of a site. Granted that byte-range slicing isn't the

most intuitive for such.



Note also that using arguments is more **useful** than byte-ranges in

the sense that they can be set in a normal link, while byte ranges

require a special [HTTP header](https://en.wikipedia.org/wiki/Byte_serving).



## Configuration example



    location ^~ /video-dump/ {

        slice; # enable slicing

        slice_start_arg s;

        slice_end_arg e;    

    }



So we would request the first 1k of the file like this:



    http://example.com/video-dump/large_vid.mp4?s=0&e=1024



Notice `s=0`, start at `0` and `e=1024`, stop at `1024` bytes (1k). 



## Module directives



**slice**



**context:** `location`



It enables the content slicing in a given location.










**slice_arg_begin** `string`



**default:** `begin`



**context:** `http, server, location`



Defines the argument that defines the request range of bytes **start**.










**slice_arg_end** `string`



**default:** `end`



**context:** `http, server, location`



Defines the argument that defines the request range of bytes **end**.










**slice_header** `string`



**context:** `http, server, location`



Defines the string to be used as the **header** of each slice being

served by Nginx.










**slice_footer** `string`



**context:** `http, server, location`



Defines the string to be used as the **footer** of each slice being

served by Nginx.










**slice_header_first** `on` | `off`



**default:** `on`



**context:** `http, server, location`



If set to `off` and when requesting the **first** byte of the file do **not

serve** the header.



This directive is particularly useful to differentiate the **first**

slice from the remaining slices. The first slice is the one which has

**no** header.










**slice_footer_last** `on` |  `off `



**default:** `on`



**context:** `http, server, location`



If set to `off` and when requesting the **last** byte of the file do **not

serve** the header.



This directive is particularly useful to differentiate the **last**

slice from the remaining slices. The last slice is the one which has

**no** footer.



## Assorted examples



Here's some examples that explore all the options.



### Serve a huge DB file while sending headers except on the first slice



    location ^~ /dbdumps/ {

        slice; # enable slicing

        slice_start_arg first;

        slice_end_arg last;

        slice_header '-- **db-slice-start**';

        slice_header_first off;

    }



Then a request like this:



    http://example.com/dbdumps/somedb.sql?first=0&last=1048576

    

Send the first 1M and skip the `-- **db-slice-start**` header.



### Serve a huge DB file while sending headers except on the first slice



    location ^~ /dbdumps/ {

        slice; # enable slicing

        slice_start_arg first;

        slice_end_arg last;

        slice_header '-- **db-slice-start**';

        slice_header_first off;

        slice_footer '-- **db-slice-end**';

    }

    

This differs from the previous in the sense that it sends a footer.



### Serve a huge DB file while sending headers except on the first slice and send footer except on the last slice



    location ^~ /dbdumps/ {

        slice; # enable slicing

        slice_start_arg first;

        slice_end_arg last;

        slice_header '-- **db-slice-start**';

        slice_header_first off;

        slice_footer '-- **db-slice-end**';

        slice_footer_last off; 

    }



Then a request like this:



    http://example.com/dbdumps/somedb.sql?first=0&last=1048576



Send the first 1M and skip the `-- **db-slice-start**` header.



If the file is 200MB, we get the last slice with:



    http://example.com/dbdumps/somedb.sql?first=208666624&last=209715200



this last slice has no footer.



## Installation



 1. Clone the git repo.

     

        git clone git://github.com/alibaba/nginx-http-slice.git



 2. Add the module to the build configuration by adding

    `--add-module=/path/to/nginx-http-slice`.



 3. Build the nginx binary.

 

 4. Install the nginx binary.

 

 5. Configure contexts where concat is enabled.

 

 6. Build your links such that the above format, i.e., all URIs that

    correspond to specific ranges. As example here's how to link to

    the first 4k of a file.

    

        db dump

              

 7. Done.   



## Tagging releases 



I'm tagging each release in synch with the

[Tengine](http://tengine.taobao.org) releases.

 

## Other tengine modules on Github



 + [http concat](https://github.com/taobao/nginx-http-concat):

   allows to concatenate a given set of files and ship a single

   response from the server. It's particularly useful for **aggregating**

   CSS and Javascript files.



 + [footer filter](https://github.com/taobao/nginx-http-footer-filter):

   allows to add some extra data (markup or not) at the end of a

   request body. It's pratical for things like adding time stamps or

   other miscellaneous stuff without having to tweak your application.



## Other builds



 1. As referred at the outset this module is part of the

    [`tengine`](http://tengine.taobao.org) Nginx distribution. So you

    might want to save yourself some work and just build it from

    scratch using `tengine` in lieu if the official Nginx source.



 2. If you fancy a bleeding edge Nginx package (from the dev releases)

    for Debian made to measure then you might be interested in my

    [debian](http://debian.taobao.net/unstable) Nginx

    package. Instructions for using the repository and making the

    package live happily inside a stable distribution installation are

    [provided](http://debian.taobao.net).

        

## Acknowledgments



Thanks to [Joshua Zhu](http://blog.zhuzhaoyuan.com) and the Taobao

platform engineering team for releasing `tengine`. Also for being kind

enough to clarify things regarding this module on the

[Tengine mailing list](http://code.taobao.org/mailman/listinfo/tengine).



## License



Copyright (C) 2010-2012 Alibaba Group Holding Limited



Redistribution and use in source and binary forms, with or without

modification, are permitted provided that the following conditions

are met:

 

 1. Redistributions of source code must retain the above copyright

    notice, this list of conditions and the following disclaimer.

    

 2. Redistributions in binary form must reproduce the above copyright

    notice, this list of conditions and the following disclaimer in the

    documentation and/or other materials provided with the distribution.



THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS "AS IS" AND ANY

EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE

LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR

BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE

OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN

IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.