合约应用主要介绍编写应用相关内容合约部署使用方式参看3.4 智能合约开发

4.1 合约范例1:电子存证合约

代码样例参看：contractsdk/go/example/eleccert.go

4.1.1 电子存证合约简介

电子存证应用主要是通过区块链解决的存证中的信任问题，而存证合约只需做简单的读写操作即可

4.1.2 电子存证合约具备的读写操作

• 通过invoke方法，put存证到区块链
• 通过query方法，get存证

4.1.3调用json文件示例

invoke

./xchain-cli native invoke -a ‘下面json中args字段的内容’ —method save -H localhost:37101 eleccert

{
    "module_name": "native",       // native or wasm
    "contract_name": "eleccert",   // contract name
    "method_name": "save",       // invoke or query
    "args": {
        "owner": "aaa",            // user name
        "filehash": "存证文件的hash值",
        "timestamp": "存证的timestamp"
    }
}

query

./xchain-cli native query -a ‘args内容’ —method query -H localhost:37101 eleccert

{
    "module_name": "native",       // native or wasm
    "contract_name": "eleccert",   // contract name
    "method_name": "query",        // invoke or query
    "args": {
        "owner": "aaa",            // user name
        "filehash": "文件hash值"
    }
}
\\ output
{
    "filehash": "文件hash值",
    "timestamp": "文件存入timestamp"
}

4.2 合约范例2:数字资产交易

代码样例参看：contractsdk/go/example/erc721.go

4.2.1 ERC721简介

ERC721是数字资产合约,交易的商品是非同质性商品其中，每一份资产，也就是token_id都是独一无二的类似收藏品交易

4.2.2 ERC721具备哪些功能

• 通过initialize方法，向交易池注入自己的token_id
  • 注意token_id必须是全局唯一
• 通过invoke方法，执行不同的交易功能
  • transfer: userA将自己的某个收藏品token_id转给userB
  • approve: userA将自己的某个收藏品token_id的售卖权限授予userB
  • transferFrom: userB替userA将赋予权限的收藏品token_id卖给userC
  • approveAll: userA将自己的所有收藏品token_id的售卖权限授予userB
• 通过query方法，执行不同的查询功能
  • balanceOf: userA的所有收藏品的数量
  • totalSupply: 交易池中所有的收藏品的数量
  • approvalOf: userA授权给userB的收藏品的数量

4.2.3调用json文件示例

initialize

./xchain-cli wasm invoke -a ‘下面json中args字段的内容’ —method initialize -H localhost:37101 erc721

{
    "module_name": "native",      // native或wasm
    "contract_name": "erc721",    // contract name
    "method_name": "initialize",  // initialize or query or invoke
    "args": {
        "from": "dudu",           // userName
        "supply": "1,2"          //  token_ids
    }
}

invoke

./xchain-cli native invoke -a ‘args内容’ —method invoke -H localhost:37101 erc721

{
    "module_name": "native",      // native或wasm
    "contract_name": "erc721",    // contract name
    "method_name": "invoke",      // initialize or query or invoke
    "args": {
        "action": "transfer",     // action name
        "from": "dudu",           // usera
        "to": "chengcheng",       // userb
        "token_id": "1"           // token_ids
    }
}
{
    "module_name": "native",      // native或wasm
    "contract_name": "erc721",    // contract name
    "method_name": "invoke",      // initialize or query or invoke
    "args": {
        "action": "transferFrom", // action name
        "from": "dudu",           // userA
        "caller": "chengcheng",   // userB
        "to": "miaomiao",         // userC
        "token_id": "1"           // token_ids
    }
}
{
    "module_name": "native",      // native或wasm
    "contract_name": "erc721",    // contract name
    "method_name": "invoke",      // initialize or query or invoke
    "args": {
        "action": "approve",      // action name
        "from": "dudu",           // userA
        "to": "chengcheng",       // userB
        "token_id": "1"           // token_ids
    }
}

query

./xchain-cli native query -a ‘args内容’ —method query -H localhost:37101 erc721

{
    "module_name": "native",     // native或wasm
    "contract_name": "erc721",   // contract name
    "method_name": "query",      // initialize or query or invoke
    "args": {
        "action": "balanceOf",   // action name
        "from": "dudu"           // userA
    }
}
{
    "module_name": "native",     // native或wasm
    "contract_name": "erc721",   // contract name
    "method_name": "query",      // initialize or query or invoke
    "args": {
        "action": "totalSupply"  // action name
    }
}
{
    "module_name": "native",      // native或wasm
    "contract_name": "erc721",    // contract name
    "method_name": "query",       // initialize or query or invoke
    "args": {
        "action": "approvalOf",   // action name
        "from": "dudu",           // userA
        "to": "chengcheng"       // userB
    }
}

4.3 智能合约sdk

systemAPI

PutObject
输入：k，v
输出：true/false
GetObject
输入：k
输出：v
DeleteObject
输入：k，v
输出：true/false