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To make it easier for users experienced in Java to connect to iPaaS, the Dataway code mode supports Java scripts.

Use of IDE

1. Hover over any Dataway textbox, and the mode selection buttons will pop up automatically. Click Code to enter the code mode.
   
2. Click the textbox, and the code editor will pop up. Click Java to enter the Java script editor.
3. After editing the script, click Confirm.

The Java code mode supports data reference on the flow data panel.

Script Structure

A Java script must be in compliance with JDK 8 syntax.

The class name must be Handler, and you must define a function with the signature Object eval(Message msg) as the entry function.

import com.tencent.ipaas.dataway.common.message.Message; 
import com.tencent.ipaas.dataway.common.message.DataRef; 

You can add other import statements based on required data types.

// The following `import` statements are fixed and cannot be deleted.
import com.tencent.ipaas.dataway.common.message.Message;
import com.tencent.ipaas.dataway.common.message.DataRef; 

/**
 * Entry class of `dataway-java`, which must be named `Handler`
 */
public class Handler {
    /**
     * Entry function, whose signature must be `Object eval(Message msg)`
     * @param msg Input a `Message` object
     * @return Any data object supported by Dataway
     */
    public Object eval(Message msg) {
        return msg.getPayload();
    }
}

Data Types

The Java code mode supports various data types, making it easy for you to manipulate different data.

Using an Entity Object

Basic methods

In Java code mode of iPaaS, the Entity type is used to represent the entity data in flows. It is an encapsulation object of binary data and contains blob, mimeType, and encoding.

You can access content in Entity as follows:

Currently, the MIME types supported for deserialization and types of the deserialized value are as listed below:

• text/plain → String
• application/json → Object, which is the same as JSON
• application/x-www-form-urlencoded → Multimap
• application/xml → Map
• application/csv → List<Map<String,String>>, i.e., list of mappings between field names and values
• multipart/form-data → FormDataParts

Constructor

Entity.fromValue static method

This method is used to encapsulate the value type data into an Entity object and return it as follows:

Entity.fromValue(Object value, String mimeType, String encoding)

The fromValue function tries serializing value based on the specified MIME and encoding types to get the data of byte[] type, encapsulates it into an Entity object, and returns the object.

• The mimeType parameter is required. Currently, six MIME types are supported: text/plain, application/json, application/x-www-form-urlencoded, application/csv, application/xml, and multipart/form-data.
• The encoding parameter is required and can be any valid encoding type.

Entity.fromBytes static method

This method is used to encapsulate a String or a byte[] object into an Entity object and return it as follows:

Entity.fromBytes(Object data, String mimeType, String encoding)

The verification rules of the MIME type and encoding type parameters in fromBytes are similar to those in the fromValue function but differ in that the value of the MIME type parameter is not limited and can be any MIME type.

• If the data parameter passed to the fromBytes function is of byte[] type, the function will directly return an Entity object consisting of parameters data, mimeType, and encoding.
• If the passed data parameter is of String type, it will be encoded as a byte[] object based on the encoding parameter and constructed as an Entity object.

Use limits

An Entity object is essentially an encapsulation object of binary data. For ease of use, object content access methods like entity.get() are provided. Before using these features, note that for some special operations, the system will try deserializing the binary data in the Entity object, and runtime errors will occur if parsing fails. Such special operations include:

• Using entity.getValue() to get the structured result after parsing.
• Using entity.get(key) to get the content of an element in the structured result.

If you perform the above special operations on a non-compliant Entity object, runtime errors will occur.