t1_resize_img01:

Create a simple HTTP server application that listens on port 8080 to serves a specific function: resizing a jpeg image, in the form of base 64 encoded binary input data to the desired target dimension. The server only needs to serve exactly single API below:

HTTP://[host_address]:8080/resize_image [POST]

Input Payload: Content-Type: application/json {

"input_jpeg": "[base 64 encoding of jpeg binary]", "target_width": [target_width], "target_height": [target_height]

}

Output Payload: If success: HTTP 200 Content-Type: application/json { "code": 200, "message": "success", "output_jpeg": "[base 64 encoding of output jpeg binary]" }

If failed: HTTP 4XX/5XX Content-Type: application/json { "code": 4xx/5xx, "Message": "[output error description here]" }

Requirements:

1. Drogon Framework https://drogon.docsforge.com/master/installation/
2. OpenCV 4.xx
3. CMake 3.2.x

Environment

$ sudo apt install git

$ sudo apt install gcc

$ sudo apt install g++

$ sudo apt install cmake

jsoncpp

$ sudo apt install libjsoncpp-dev

uuid

$ sudo apt install uuid-dev

OpenSSL

$ sudo apt install openssl

$ sudo apt install libssl-dev

zlib

$ sudo apt install zlib1g-dev

Database Environment

PostgreSQL

$ sudo apt-get install postgresql-all

$ su postgres

Sqlite3

$ sudo apt-get install libsqlite3-dev

Drogon Installation

Assuming that the above environment and library dependencies are all ready, the installation process is very simple; Install by source in Linux

---

$cd $WORK_PATH

$ git clone https://github.com/an-tao/drogon

$ cd drogon

$ git submodule update --init

$ mkdir build

$ cd build

$ cmake ..

$ make && sudo make install

The default is to compile the debug version. If you want to compile the release version, the cmake command should take the following parameters: cmake -DCMAKE_BUILD_TYPE=Release ..

After the installation is complete, the following files will be installed in the system（One can change the installation location with the CMAKE_INSTALL_PREFIX option）:

The header file of drogon is installed into /usr/local/include/drogon;
The drogon library file libdrogon.a is installed into /usr/local/lib;
Drogon's command line tool drogon_ctl is installed into /usr/local/bin;
The trantor header file is installed into /usr/local/include/trantor;
The trantor library file libtrantor.a is installed into /usr/local/lib;

Building OpenCV from Source on Linux ( Ubuntu 20.0 LTS )

$ sudo apt update

$ wget -O opencv-4.5.5.zip https://github.com/opencv/opencv/archive/4.5.5.zip

$ unzip opencv-4.5.5.zip

$ cd opencv-4.5.5

$ mkdir build

$ cd build

Below command is normally used for configuration of OpenCV library build (executed from build folder): $ cmake ../

OpenCV defaults assume "Release" build type and installation path is "/usr/local". For additional information about CMake options refer to OpenCV C++ compilation guide:

$ make

$ sudo make install

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Create symlink Since OpenCV4 include file in /usr/local/include/opencv4/opencv2 . We create symlink:

$ sudo ln -s /usr/local/include/opencv4/opencv2 /usr/local/include/opencv2

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This program is tested under Linux Ubuntu 20 LTS,running on VirtualBox Windows 10 Hosts