铂链第4课 如何在BOTTOS实现最简智能合约"Hello World"？

1，摘要

本文假设你已经完成了铂链本地节点部署和账户创建，没有完成的话，参考《铂链第3课 BOTTOS账户体系(密钥对/账号/钱包)的创建和管理》完成相关准备工作。
本文的主要内容包括：
（1）用C++创建"Hello World"合约
（2）编译wasm和ABI文件
（3）部署和运行合约

2，内容

2.1 前置条件-本地节点启动和账户创建

1）启动本地节点

参考《铂链第2课 如何部署节点并加入BOTTOS测试网络？》 完成本地节点部署。
启动本地节点

./bottos --delegate=bottos --enable-wallet

2）创建账户，质押BTO

请参考《铂链第3课 BOTTOS账户体系(密钥对/账号/钱包)的创建和管理》 完成用户账号的创建，从系统账号转账一定的BTO并质押200个BTO。

账户信息：
账号名称: wangdenghui
密钥对：
public_key: 049b98b5f5eea7fd5145842d08f8cd25052f69e731f9f550ac8a2e37792e165cf13fbc52ad7dad32eaa192799601b4cc35eab1923e007048f9d47c80aa4bf9cb8d
private_key: 1d2533b83d5c811b53b7503aad9488310631b705e9df12bbce8c03149be559fd
账户余额：800BTO
质押情况：100 BTO for time; 100 BTO for space；

2.2 创建合约

C++和C语言的语法，辉哥就不展开分析了。假设我们创建了相关的文件。

1） testHelloWorld.cpp

三个函数，打印“hello world...”出来。

#include "contractcomm.hpp"

extern "C" {
    int start();
    int add();
    int del();
}

int start() 
{
    myprints("hello world in start");
    
    return 0;
}

int add() 
{
    myprints("hello world in add");
    
    return 0;
}

int del() 
{
    myprints("hello world in del");
    
    return 0;
}

2） testHelloWorld.h

头文件定义

//@abi action start
struct NullStruct {
};

2.3 编译产生wasm和ABI文件

（1）制定合约工作目录和下载编译版本

假设我们创建/home/duncanwang/go/work目录作为BOTOS工作目录。
在工作目录下，下载编译工具：

git clone https://github.com/bottos-project/contract-tool-cpp.git

【成功执行结果】

duncanwang@ubuntu64bit-server:~/go/work$ git clone https://github.com/bottos-project/contract-tool-cpp.git
Cloning into 'contract-tool-cpp'...
remote: Enumerating objects: 31, done.
remote: Counting objects: 100% (31/31), done.
remote: Compressing objects: 100% (21/21), done.
remote: Total 237 (delta 16), reused 23 (delta 10), pack-reused 206
Receiving objects: 100% (237/237), 26.89 MiB | 2.02 MiB/s, done.
Resolving deltas: 100% (128/128), done.
Checking out files: 100% (41/41), done.

(2) 编译合约产生WASM文件

上面合约代码其实铂链的编译工具已经自带了，辉哥就不重复上传了。只是提示下，如果发生Access Denied的问题，记得chmod 777修改文件读写属性即可。
进入合约目录testHelloWorld,然后运行下面命令编译合约

python ../gentool.py --type wasm --file testHelloWorld.cpp

运行后，新的testHelloWorld.wasm和testHelloWorld.wast已经产生了。

【成功结果】

duncanwang@ubuntu64bit-server:~/go/work/contract-tool-cpp/testHelloWorld$ python ../gentool.py --type wasm --file testHelloWorld.cpp
../bin/clang -emit-llvm -O3 --std=c++14 --target=wasm32 -ffreestanding -nostdlib -fno-threadsafe-statics -fno-rtti -fno-exceptions -I ../lib -I . -c testHelloWorld.cpp -o ./tmpdir/build/testHelloWorld.cpp
In file included from testHelloWorld.cpp:1:
../lib/contractcomm.hpp:181:22: warning: ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
            myprints("ERROR: Get my contract name failed.");
                     ^
../lib/contractcomm.hpp:196:18: warning: ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
        myprints("getBinValue failed!");
                 ^
testHelloWorld.cpp:11:14: warning: ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
    myprints("hello world in start");
             ^
testHelloWorld.cpp:18:14: warning: ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
    myprints("hello world in add");
             ^
testHelloWorld.cpp:25:14: warning: ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
    myprints("hello world in del");
             ^
5 warnings generated.
../bin/llvm-link -o ./tmpdir/linked.bc ./tmpdir/build/*
../bin/llc --asm-verbose=false -o ./tmpdir/assembly.s ./tmpdir/linked.bc
../bin/s2wasm -o testHelloWorld.wast -s 16384 ./tmpdir/assembly.s

常见问题及解决方案

1）【失败结果】- python未安装

duncanwang@ubuntu64bit-server:~/go/work/contract-tool-cpp$ python

Command 'python' not found, but can be installed with:

sudo apt install python3       
sudo apt install python        
sudo apt install python-minimal

You also have python3 installed, you can run 'python3' instead.

【安装出错】

duncanwang@ubuntu64bit-server:~/go/work$ sudo apt install python   
[sudo] password for duncanwang: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
  libpython-stdlib libpython2.7-minimal libpython2.7-stdlib python-minimal python2.7 python2.7-minimal
Suggested packages:
  python-doc python-tk python2.7-doc binutils binfmt-support
The following NEW packages will be installed:
  libpython-stdlib libpython2.7-minimal libpython2.7-stdlib python python-minimal python2.7 python2.7-minimal
0 upgraded, 7 newly installed, 0 to remove and 75 not upgraded.
Need to get 3,949 kB of archives.
After this operation, 16.8 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:3 http://archive.ubuntu.com/ubuntu bionic/main amd64 python-minimal amd64 2.7.15~rc1-1 [28.1 kB]
Get:4 http://archive.ubuntu.com/ubuntu bionic/main amd64 libpython2.7-stdlib amd64 2.7.15~rc1-1 [1,910 kB]
Get:7 http://archive.ubuntu.com/ubuntu bionic/main amd64 python amd64 2.7.15~rc1-1 [140 kB]                                              
Err:1 http://archive.ubuntu.com/ubuntu bionic/main amd64 libpython2.7-minimal amd64 2.7.15~rc1-1                                                                                              
  502  Bad Gateway [IP: 117.143.109.143 80]
Err:2 http://archive.ubuntu.com/ubuntu bionic/main amd64 python2.7-minimal amd64 2.7.15~rc1-1                                                                                                 
  502  Bad Gateway [IP: 117.143.109.142 80]
Get:5 http://archive.ubuntu.com/ubuntu bionic/main amd64 python2.7 amd64 2.7.15~rc1-1 [238 kB]                                                                                                
Get:6 http://archive.ubuntu.com/ubuntu bionic/main amd64 libpython-stdlib amd64 2.7.15~rc1-1 [7,620 B]                                                                                        
Fetched 2,324 kB in 17s (136 kB/s)                                                                                                                                                            
E: Failed to fetch http://117.143.109.143/cache/archive.ubuntu.com/ubuntu/pool/main/p/python2.7/libpython2.7-minimal_2.7.15~rc1-1_amd64.deb?ich_args2=144-13213206052547_3259d609842731f004706c767b1bb39a_10001002_9c89602ed6c2f4d8903c518939a83798_5a2e3e24305ad5ad963c61d5902f3d1f  502  Bad Gateway [IP: 117.143.109.143 80]
E: Failed to fetch http://117.143.109.142/cache/archive.ubuntu.com/ubuntu/pool/main/p/python2.7/python2.7-minimal_2.7.15~rc1-1_amd64.deb?ich_args2=144-13213210052808_ca0ba91cda916deada222929a3eb7ae4_10001002_9c89602ed6c2f4d8903c518939a83798_6d64072715e5c504a601fe11b7a54dbe  502  Bad Gateway [IP: 117.143.109.142 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

【翻墙-安装成功有输出】

duncanwang@ubuntu64bit-server:~/go/work$ sudo apt install python
[sudo] password for duncanwang: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
  libpython-stdlib libpython2.7-minimal libpython2.7-stdlib python-minimal python2.7 python2.7-minimal
Suggested packages:
  python-doc python-tk python2.7-doc binutils binfmt-support
The following NEW packages will be installed:
  libpython-stdlib libpython2.7-minimal libpython2.7-stdlib python python-minimal python2.7 python2.7-minimal
0 upgraded, 7 newly installed, 0 to remove and 75 not upgraded.
Need to get 334 kB/3,949 kB of archives.
After this operation, 16.8 MB of additional disk space will be used.
Do you want to continue? [Y/n] Y
Get:1 http://archive.ubuntu.com/ubuntu bionic/main amd64 libpython2.7-minimal amd64 2.7.15~rc1-1 [334 kB]
Fetched 334 kB in 3s (124 kB/s)                
Selecting previously unselected package libpython2.7-minimal:amd64.
(Reading database ... 102201 files and directories currently installed.)
Preparing to unpack .../0-libpython2.7-minimal_2.7.15~rc1-1_amd64.deb ...
Unpacking libpython2.7-minimal:amd64 (2.7.15~rc1-1) .......................................................................................................................................] 
Selecting previously unselected package python2.7-minimal..................................................................................................................................] 
...
Processing triggers for mime-support (3.60ubuntu1) ...##########################################################################################...........................................] 
Processing triggers for man-db (2.8.3-2) ...
Setting up libpython2.7-stdlib:amd64 (2.7.15~rc1-1) ...
Setting up python2.7 (2.7.15~rc1-1) ...###################################################################################################################.................................] 
Setting up libpython-stdlib:amd64 (2.7.15~rc1-1) ...###############################################################################################################........................] 
Setting up python (2.7.15~rc1-1) ...########################################################################################################################################...............] 

2）文件目录不正确

【错误输出】

duncanwang@ubuntu64bit-server:~/go/work/RegUser$ python ~/go/work/contract-tool-cpp/gentool.py wasm testRegUser.cpp
Error! Please keep these files [clang | llc | llvm-link | s2wasm] under current directory.

【解决方法】
工作目录要建立在~/go/work/contract-tool-cpp下，不要建立在其他地方。

(3) 编译合约产生ABI文件

运行以下命令产生ABI文件。

python ../gentool.py --file testHelloWorld.hpp

【成功结果】

duncanwang@ubuntu64bit-server:~/go/work/contract-tool-cpp/testHelloWorld$ python ../gentool.py --file testHelloWorld.hpp

[ testHelloWorld.abi ] is generated. Please have a check.

下载已产生的ABI，可以看到testHelloWorld.abi内容如下：

{
    "types": [],
    "structs": [
              {
                "name": "NullStruct",
                "base": "",
                "fields": {
                    }
                }
       ],
    "actions": [
              {
                "action_name": "start",
                "type": "NullStruct"
              }
       ],
    "tables": [
       ]
}

简单介绍一下abi文件的组成:

structs ：扫描出来的结构体的定义描述，这儿是"NullStruct"，供后面使用；
actions：合约提供的方法描述，其中action_name 是方法名，例如 "start"函数， type 是调用合约所要的参数；
tables ：合约持久化数据访问接口描述，即合约保存的数据描述，其中table_name 是表名，index_type 是索引的类型， key_names 和key_types 分别是键值的名称和类型，type 是保存的数据的结构定义。

abi文件是通过扫描hpp文件生成， 在hpp文件里通过注释来告诉扫描器具体的定义：

"//@abi action start"：
​ 本合约定义了两个方法，其中start 对应的入参定义为NullStruct；

”//@abi table testTableName:[index_type:string, key_names:keyName, key_types:string] “
​ 定义了一个表， 表内容的结构体定义为testTableName 。本案例不存在。

2.3 部署和运行合约

（1）部署智能合约与ABI文件

部署合约d的命令如下，该命令成功后将返回BCLI成功发送的Transaction信息。

./bcli contract deploy

参数描述如下：
--contract 合约名
--code 合约文件（.WASM）所在路径
--filetype 合约文件类型：wasm/js
--abi 合约文件（.abi）
--account 部署合约的账户

在操作前，需要把bcli 命令从BOTTOS安装环境复制过来。

duncanwang@ubuntu64bit-server:~/go/work/contract-tool-cpp/testHelloWorld$ cp /home/duncanwang/go/src/github.com/bottos/bcli .

然后，把wangdenghui账号unlock，把部署的合约取名为babycry,样例命令如下：

./bcli contract deploy --contract babycry --account wangdenghui --code testHelloWorld.wasm --abi testHelloWorld.abi

【成功交易结果】

duncanwang@ubuntu64bit-server:~/go/work/contract-tool-cpp/testHelloWorld$ ./bcli contract deploy --contract babycry --account wangdenghui --code testHelloWorld.wasm --abi testHelloWorld.abi

TrxHash: fc5527e0600b353c0c38c87b64ec29c8b8856fc36ec83575f916b1cc556def7f

This transaction is sent. Please check its result by command : bcli transaction get --trxhash  

【查询交易结果】

./bcli transaction get --trxhash fc5527e0600b353c0c38c87b64ec29c8b8856fc36ec83575f916b1cc556def7f

【结果】

duncanwang@ubuntu64bit-server:~/go/work/contract-tool-cpp/testHelloWorld$ ./bcli transaction get --trxhash  fc5527e0600b353c0c38c87b64ec29c8b8856fc36ec83575f916b1cc556def7f
{
    "ResourceReceipt": {
        "account_name": "wangdenghui",
        "space_token_cost": 2138,
        "time_token_cost": 100
    },
    "Transaction": {
        "contract": "bottos",
        "cursor_label": 1543494136,
        "cursor_num": 5304,
        "lifetime": 1546681090,
        "method": "deploycontract",
        "param": {
            "contract": "babycry",
            "contract_abi": "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",
            "contract_code": "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",
            "vm_type": 1,
            "vm_version": 1
        },
        "sender": "wangdenghui",
        "sig_alg": 1,
        "signature": "65b8fe0a75949e3250ae1074234989fc3850af7179ef184d233e0c15d7e5a3025e7c343b557756af3e516b16cdda126c7f9728a65788a73ed6e8f4ba49890a9c",
        "version": 65536
    },
    "TrxHash": "fc5527e0600b353c0c38c87b64ec29c8b8856fc36ec83575f916b1cc556def7f"
}

<<>> : commited

【提醒】
如果已把bcli复制到系统bin文件夹，则直接执行bcli ...，如果是复制到工作目录，则需要输入./bcli ...格式。

复制bcli命令到本地工程目录，命令调用格式：./bcli ...

cp /home/duncanwang/go/src/github.com/bottos/bcli .

复制到可执行文件夹，命令调用格式：bcli ...

cp /home/duncanwang/go/src/github.com/bottos/bcli /usr/bin/.

【常见错误提示】

duncanwang@ubuntu64bit-server:~/go/work/contract-tool-cpp/testHelloWorld$ ./bcli contract deploy --contract babyContract --account wangdenghui --code testHelloWorld.wasm --abi testHelloWorld.abi
Error: Please input the correct contract's name, [a-z,0-9], 3-10 character, begin with a-z

【分析说明】
合约名称不超过10个字符，只能是小写字母和数字[a-z,0-9]，这个太戏剧了，10个字符能表达一个好的合约名字吗？建议铂链采用不超过32个字符的名字均可。

（2）运行合约

运行合约的命令如下，该命令成功后将返回指定Trxhash对应的Transaction信息。

./bcli transaction push

参数说明：
--sender 签名发起者（缺省为内置bottos用户）
--contract 合约名,格式为合约名@部署账户
--method 合约方法名
--param 参数键值对
--sign 用户自定义公钥（缺省为内置缺省值）

【运行合约样例】

./bcli transaction push --sender wangdenghui --method start --contract babycry@wangdenghui

【执行成功结果】

duncanwang@ubuntu64bit-server:~/go/work/contract-tool-cpp/testHelloWorld$ ./bcli transaction push --sender wangdenghui --method start --contract babycry@wangdenghui

TrxHash: 50226dc38a102b4dd848ecebbf3cb3668886f7b0f10158acd435e315efcb930a

This transaction is sent. Please check its result by command : bcli transaction get --trxhash  

【查看合约是否部署成功】

./bcli  transaction  get --trxhash  "50226dc38a102b4dd848ecebbf3cb3668886f7b0f10158acd435e315efcb930a"

duncanwang@ubuntu64bit-server:~/go/work/contract-tool-cpp/testHelloWorld$ ./bcli  transaction  get --trxhash  "50226dc38a102b4dd848ecebbf3cb3668886f7b0f10158acd435e315efcb930a"

<<>> : commited


./bcli  gettable --account wangdenghui --table testTableName --key testKeyName

./bcli  transaction  get --trxhash  "c0780dd99c1d38b613cc3c644309a897b022dfbcf45c029ee7e1b701aa6385db"

【重大疑问】-输出并没有"hello world"的打印

BOTTOS的命令行输出没有Info打印信息，所有信息都在~/go/src/github.com/bottos/datadir/log的bottos.log文件显示。
但是默认情况下不显示info信息，需要执行命令改变。

修改LOG输出等级的命令：

./bcli log setconfigitem

参数说明：
--key 日志参数，选其一设置：minlevel maxlevel
--value 按日志参数，填写对应项值
例如：
./bcli log setconfigitem --key minlevel --value debug

【调整LOG等级输出结果】

duncanwang@ubuntu64bit-server:~/go/work/contract-tool-cpp/testHelloWorld$ ./bcli log  setconfigitem --key minlevel --value debug
{
    "errcode": 0
}
setconfigitem successfully.

再执行合约。
然后再执行./bcli transaction push命令，就可以在bottos.log文件搜索"hello world in start"关键字可以看到对应的"hello world ..."打印。
如下：

2019-01-05 10:39:21.173 [INF] res-processor.go:444 GetUserFreeTimeLimit(): RESOURCE:GetUserFreeTime account:wangdenghui, limit:{Available:202 Used:198 Max:400}
2019-01-05 10:39:21.173 [INF] res-processor.go:420 GetUserTimeLimit(): RESOURCE:GetUserTimeLimit account:wangdenghui, limit:{Available:28799999709 Used:291 Max:28800000000}
2019-01-05 10:39:21.174 [INF] env_func.go:442 prints(): VM prints value hello world in start

至此，BOTTOS最简合约的编写及运行讲解完毕。

3，参考

1） 铂链官网
http://www.bottos.org/
2）铂链开发手册
https://docs.botfans.org/en/
3）铂链GITHUB
https://github.com/bottos-project
4）研发帮助文档
https://github.com/bottos-project/Documentation/tree/master/resource_cn
5）BCLI使用说明
https://github.com/bottos-project/Documentation/blob/master/resource_cn/BCLI%E4%BD%BF%E7%94%A8%E8%AF%B4%E6%98%8E.md

本篇文章得到铂链技术专家张伟的指导，谨表感谢。

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