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File Connector Example¶

File Connector can be used to perform operations in the local file system as well as in a remote server such as FTP and SFTP.

What you'll build¶

This example explains how to use File Connector to create a file in the local file system and read the particular file. The user sends a payload specifying which content is to be written to the file. Based on that content, a file is created in the specified location. Then the content of the file can be read as an HTTP response by invoking the other API resource upon the existence of the file.

It will have two HTTP API resources, which are create and read.

/create: The user sends the request payload which includes the location where the file needs to be saved and the content needs to be added to the file. This request is sent to WSO2 EI by invoking the FileConnector API. It saves the file in the specified location with the relevant content.
/read: The user sends the request payload, which includes the location of the file that needs to be read. This request is sent to WSO2 EI where the FileConnector API resides. Once the API is invoked, it first checks if the file exists in the specified location. If it exists, the content is read and response is sent to the user. If the file does not exist, it sends an error response to the user.

If you do not want to configure this yourself, you can simply get the project and run it.

Configure the connector in WSO2 Integration Studio¶

Follow these steps to set up the Integration Project and the Connector Exporter Project.

{!references/connectors/importing-connector-to-integration-studio.md!}

Creating the Integration Logic¶

Right click on the created Integration Project and select, -> New -> Rest API to create the REST API.
Provide the API name as File Connector and the API context as /fileconnector.
First we will create the /create resource. Right click on the API Resource and go to Properties view. We use a URL template called /create as we have two API resources inside single API. The method will be Post.
In this operation we are going to receive input from the user which is source and inputContent.
- source - location that the file is going to be created.
- inputContent - what needs to be written to the file.
The above two parameters are saved to properties. Drag and drop the Property Mediator onto the canvas in the design view and do as shown below. For further reference, you can read about the Property mediator.
Add the another Property Mediator to get the InputContent value copied. Do the same as in the above step.
- property name: InputContent
- Value Type: EXPRESSION
- Value Expression: json-eval($.inputContent)
Drag and drop the create operation of the File Connector to the Design View as shown below. Set the parameter values as below. We use the property values that we added in step 4 and 5 in this step as $ctx:source and $ctx:inputContent.
Add a Respond Mediator as the user needs to see the response. Now we are done with creating the first API resource, and it is displayed as shown below.
Create the next API resource, which is /read. From this we are going to read the file content from a user specified location.
As described in step 3, drag and drop another API resource to the design view. Use the URL template as /read. The method will be POST.
In this operation, the user sends the file location as the request payload. It will be written to the property as we did in step 10.
Then we are going to check if the file actually exists in the specified location. We can use isFileExists operation of the File Connector.
Then we copy the isFileExists response to a property mediator. Add another property mediator and add values as shown below.
Based on its response, we decide if we read the file or print an error to the user. In this case, we use a Switch Mediator.
Drag and drop the read operation to the case in the Switch mediator. In the default case log an error and drops the message.

You can find the complete API XML configuration below. You can go to the source view and copy paste the following config.

<?xml version="1.0" encoding="UTF-8"?>
<api context="/fileconnector" name="FileConnector" xmlns="http://ws.apache.org/ns/synapse">
    <resource methods="POST" uri-template="/create">
        <inSequence>
            <property expression="json-eval($.source)" name="source" scope="default" type="STRING"/>
            <property expression="json-eval($.inputContent)" name="inputContent" scope="default" type="STRING"/>
            <fileconnector.create>
                <source>{$ctx:source}</source>
                <inputContent>{$ctx:inputContent}</inputContent>
            </fileconnector.create>
            <respond/>
        </inSequence>
        <outSequence/>
        <faultSequence/>
    </resource>
    <resource methods="POST" uri-template="/read">
        <inSequence>
            <property expression="json-eval($.source)" name="source" scope="default" type="STRING"/>
            <fileconnector.isFileExist>
                <source>{$ctx:source}</source>
            </fileconnector.isFileExist>
            <property expression="json-eval($.fileExist)" name="response" scope="default" type="STRING"/>
            <log level="custom">
                <property expression="get-property('response')" name="responselog"/>
            </log>
            <switch source="get-property('response')">
                <case regex="true">
                    <fileconnector.read>
                        <source>{$ctx:source}</source>
                    </fileconnector.read>
                    <respond/>
                </case>
                <default>
                    <log>
                        <property name="notext" value="&quot;File does not exist&quot;"/>
                    </log>
                    <drop/>
                </default>
            </switch>
        </inSequence>
        <outSequence/>
        <faultSequence/>
    </resource>
</api>

{!references/connectors/exporting-artifacts.md!}

Get the project¶

You can download the ZIP file and extract the contents to get the project code.

Deployment¶

Follow these steps to deploy the exported CApp in the Enterprise Integrator Runtime.

{!references/connectors/deploy-capp.md!}

Testing¶

File Create Operation¶

Create a file called data.json with the following payload.

{
    "source":"/Users/IsuruUyanage/Desktop/RnD/2020/Q1/ConnectorVerification/create.txt",
    "inputContent": "This is a test file"
}

Invoke the API as shown below using the curl command. Curl Application can be downloaded from [here] (https://curl.haxx.se/download.html).
```
curl -H "Content-Type: application/json" --request POST --data @data.json http://10.100.5.136:8290/fileconnector/create
```
Expected Response: You should get a 'Success' response, and the file should be created in the specified location in the above payload.

File Read Operation¶

Create a file called data.json with the following payload.

{
    "source":"/Users/IsuruUyanage/Desktop/RnD/2020/Q1/ConnectorVerification/create.txt"
}

Invoke the API as shown below using the curl command. Curl Application can be downloaded from [here] (https://curl.haxx.se/download.html).
```
curl -H "Content-Type: application/json" --request POST --data @data.json http://10.100.5.136:8290/fileconnector/read
```

Expected Response: You should get the following text returned.

This is a test file.

What's Next¶

You can deploy and run your project on Docker or Kubernetes.
To customize this example for your own scenario, see File Connector Configuration documentation for all operation details of the connector.

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