schain_sdk/README.en.md

sdk for schain

# schain-sdk

SChain Javascript SDK, provides a set of wrapper functions that help you accessing your chaincode.

## Prerequisite
An API KEY and an APP ID are required while using the SDK. Read the [Get started](https://github.com/issbgkh/schain-get-started) guide to get them.

## Install package
npm i schain_sdk

## Usage

### Import package
```javascript
const schain = require('schain_sdk');
```
### Initialize
```javascript
// Replace API_KEY and APP_ID with yours
const API_KEY = '5d5b9cbd55cc6725f82dabba0632fe6e';
const APP_ID = 'app-38b30623-c207-4025-8c80-69df51f822c2';

schain.init(API_KEY, APP_ID)
```

## Simple store template
The SDK provides a set of convenient functions that support the [simple store template](https://github.com/issbgkh/simple-store) chaincode.

### Set a value
```javascript
let key = 'key1';
let value = '100';

await schain.set(key, value).then(result => {
    console.log('done');
}).catch(error => {
    console.log(error);
});
```

### Get a value
```javascript
let key = 'key1';

await schain.get(key).then(value => {
    console.log('value=' + value);
}).catch(error => {
    console.log(error);
});
```

### Delete a value
```javascript
let key = 'key1';

await schain.delete(key).then(result => {
    console.log(result);
}).catch(error => {
    console.log(error);
});
```

## Custom chaincode

Not only the chaincode template, the SDK also supports your custom chaincode.

With the SDK, you can invoke and query functions defined in your custom chaincode.

### Register an user
If your apps need to distinguish user identities, you can register an user by calling **register**.

```javascript
let username = 'user01';

await schain.register(username).then(result => {
    console.log('done');
}).catch(error => {
    console.log(error);
});
```

### Invoke a chaincode function
Invoke a chaincode function to update the blockchain ledger data.

```javascript
// Specify an user identity that is used to invoke the chaincode function.
// A null value is allowed if user identity is not that important for this function.
let username = 'user01';

// The function name to be invoked
let func = 'invoke';

// The arguments to be passed to the function
let args = ['a', 'b', 'c'];

await schain.invokeChainCode(username, func, args).then(result => {
    console.log('done');
}).catch(error => {
    console.log(error);
});
```

### Query a chaincode function
Query blockchain ledger data by querying a chaincode function.

```javascript
// Specify an user identity that is used to query the chaincode function.
// A null value is allowed if user identity is not that important for this function.
let username = 'user01';

// The function name to be queried
let func = 'query';

// The arguments to be passed to the function
let args = ['a'];

await schain.queryChainCode(username, func, args).then(result => {
    console.log(result);
}).catch(error => {
    console.log(error);
});
```

## License
Copyright 2019 S-Chain Technologies Limited

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.