Overview

In this lab, you'll add the ability to return XML instead of JSON.

Objectives

In this lab, you learn how to perform the following tasks:

• Use the Accept header to determine the response format.
• Convert between XML and JSON.

Setup

For each lab, you get a new Google Cloud project and set of resources for a fixed time at no cost.

1. Sign in to Qwiklabs using an incognito window.

2. Note the lab's access time (for example, 1:15:00), and make sure you can finish within that time.
   There is no pause feature. You can restart if needed, but you have to start at the beginning.

3. When ready, click Start lab.

4. Note your lab credentials (Username and Password). You will use them to sign in to the Google Cloud Console.

5. Click Open Google Console.

6. Click Use another account and copy/paste credentials for this lab into the prompts.
   If you use other credentials, you'll receive errors or incur charges.

7. Accept the terms and skip the recovery resource page.

Activate Google Cloud Shell

Google Cloud Shell is a virtual machine that is loaded with development tools. It offers a persistent 5GB home directory and runs on the Google Cloud.

Google Cloud Shell provides command-line access to your Google Cloud resources.

1. In Cloud console, on the top right toolbar, click the Open Cloud Shell button.

   

2. Click Continue.

It takes a few moments to provision and connect to the environment. When you are connected, you are already authenticated, and the project is set to your PROJECT_ID. For example:

gcloud is the command-line tool for Google Cloud. It comes pre-installed on Cloud Shell and supports tab-completion.

• You can list the active account name with this command:

gcloud auth list

Output:

Credentialed accounts: - @.com (active)

Example output:

Credentialed accounts: - google1623327_student@qwiklabs.net

• You can list the project ID with this command:

gcloud config list project

Output:

[core] project =

Example output:

[core] project = qwiklabs-gcp-44776a13dea667a6 Note: Full documentation of gcloud is available in the gcloud CLI overview guide .

Preloaded assets

These assets have already been added to the Apigee organization:

• The retail-v1 API proxy
• The oauth-v1 API proxy (for generating OAuth tokens)
• The TS-Retail target server in the eval environment (used by retail-v1)

These assets will be added to the Apigee organization as soon as the runtime is available:

• The API products, developer, and developer app (used by retail-v1)
• The ProductsKVM key value map in the eval environment (used by retail-v1)
• The ProductsKVM key value map entries backendId and backendSecret

The highlighted items are used during this lab.

Note: Revision 1 of the retail-v1 proxy is marked as deployed, and is immutable. If you ever make a mistake in your proxy code that you can't recover from, you can select revision 1 and restart editing from there.

Task 1. Add a JSONtoXML policy for converting the response

In this task, you use a JSONtoXML policy to convert the response to XML if the client has requested XML in the Accept header.

Note: In a production proxy, you should allow the client to provide XML as input by specifying application/xml in the Content-Type header. You should also add error checking to reject requests that specify a Content-Type or Accept header with a type other than JSON or XML.

Pin the Apigee console page

1. In the Google Cloud console, on the Navigation menu (), look for Apigee in the Pinned Products section.

   The Apigee console page will open.

2. If Apigee is not pinned, search for Apigee in the top search bar and navigate to the Apigee service.

3. Hover over the name, then click the pin icon ().

   The Apigee console page will now be pinned to the Navigation menu.

Add the JSONtoXML policy

1. On the left navigation menu, select Proxy development > API proxies.

2. Select the retail-v1 proxy.

3. Click the Develop tab.

   You are modifying the version of the retail-v1 proxy that was created during Labs 1 through 6.

4. Click Proxy endpoints > default > PostFlow.

5. On the Response PostFlow flow, click Add Policy Step (+).

   

6. In the Add policy step pane, select Create new policy, and then select Mediation > JSON To XML.

7. Specify the following values:

   Property	Value
   Name	J2X-Convert
   Display name	J2X-Convert
   Condition	request.header.Accept == "application/xml"

   The condition ensures that the policy executes only if the client requested XML.

8. Click Add.

   The condition is visible in the default proxy endpoint XML file.

   The PostFlow XML representation is:

   <PostFlow name="PostFlow"> <Request/> <Response> <Step> <Condition>request.header.Accept == "application/xml"</Condition> <Name>J2X-Convert</Name> </Step> </Response> </PostFlow>

9. Click Policies > J2X-Convert.

10. Change the policy configuration to:

    <JSONToXML continueOnError="false" enabled="true" name="J2X-Convert"> <Options> <InvalidCharsReplacement>_</InvalidCharsReplacement> <ObjectRootElementName>response</ObjectRootElementName> <Indent>true</Indent> </Options> <OutputVariable>response</OutputVariable> <Source>response</Source> </JSONToXML>

    This policy will convert JSON to XML. The name of the root element will be response, and Indent=true formats the XML for easier reading.

11. Click Save, and then click Save as New Revision.

12. Click Deploy.

13. To specify that you want the new revision deployed to the eval environment, select eval as the Environment, and then click Deploy.

Check deployment status

A proxy that is deployed and ready to take traffic will show a green status on the Overview tab.

When a proxy is marked as deployed but the runtime is not yet available and the environment is not yet attached, you may see a red warning sign. Hold the pointer over the Status icon to see the current status.

If the proxy is deployed and shows as green, your proxy is ready for API traffic. If your proxy is not deployed because there are no runtime pods, you can check the provisioning status.

Check provisioning status

• In Cloud Shell, to confirm that the runtime instance has been installed and the eval environment has been attached, run the following commands:

  export PROJECT_ID=$(gcloud config list --format 'value(core.project)'); echo "PROJECT_ID=${PROJECT_ID}"; export INSTANCE_NAME=eval-instance; export ENV_NAME=eval; export PREV_INSTANCE_STATE=; echo "waiting for runtime instance ${INSTANCE_NAME} to be active"; while : ; do export INSTANCE_STATE=$(curl -s -H "Authorization: Bearer $(gcloud auth print-access-token)" -X GET "https://apigee.googleapis.com/v1/organizations/${PROJECT_ID}/instances/${INSTANCE_NAME}" | jq "select(.state != null) | .state" --raw-output); [[ "${INSTANCE_STATE}" == "${PREV_INSTANCE_STATE}" ]] || (echo; echo "INSTANCE_STATE=${INSTANCE_STATE}"); export PREV_INSTANCE_STATE=${INSTANCE_STATE}; [[ "${INSTANCE_STATE}" != "ACTIVE" ]] || break; echo -n "."; sleep 5; done; echo; echo "instance created, waiting for environment ${ENV_NAME} to be attached to instance"; while : ; do export ATTACHMENT_DONE=$(curl -s -H "Authorization: Bearer $(gcloud auth print-access-token)" -X GET "https://apigee.googleapis.com/v1/organizations/${PROJECT_ID}/instances/${INSTANCE_NAME}/attachments" | jq "select(.attachments != null) | .attachments[] | select(.environment == \"${ENV_NAME}\") | .environment" --join-output); [[ "${ATTACHMENT_DONE}" != "${ENV_NAME}" ]] || break; echo -n "."; sleep 5; done; echo "***ORG IS READY TO USE***";

  When the script returns ORG IS READY TO USE, you can proceed to the next steps.

While you are waiting

Read:

• JSONtoXML policy
• XMLtoJSON policy
• Converting between XML and JSON

Task 2. Test the retail API

In this task, you validate that the retail API can return XML when requested.

Test the API proxy using private DNS

The eval environment in the Apigee organization can be called using the hostname eval.example.com. The DNS entry for this hostname has been created within your project, and it resolves to the IP address of the Apigee runtime instance. This DNS entry has been created in a private zone, which means it is only visible on the internal network.

Cloud Shell does not reside on the internal network, so Cloud Shell commands cannot resolve this DNS entry. A virtual machine (VM) within your project can access the private zone DNS. A virtual machine named apigeex-test-vm was automatically created for this purpose. You can make API proxy calls from this machine.

The curl command will be used to send API requests to an API proxy. The -k option for curl tells it to skip verification of the TLS certificate. For this lab, the Apigee runtime uses a self-signed certificate. For a production environment, you should use certificates that have been created by a trusted certificate authority (CA).

1. In Cloud Shell, open a new tab, and then open an SSH connection to your test VM:

   TEST_VM_ZONE=$(gcloud compute instances list --filter="name=('apigeex-test-vm')" --format "value(zone)") gcloud compute ssh apigeex-test-vm --zone=${TEST_VM_ZONE} --force-key-file-overwrite

   The first gcloud command retrieves the zone of the test VM, and the second opens the SSH connection to the VM.

2. If asked to authorize, click Authorize.

   For each question asked in the Cloud Shell, click Enter or Return to specify the default input.

   Your logged in identity is the owner of the project, so SSH to this machine is allowed.

   Your Cloud Shell session is now running inside the VM.

Store the app's key in a shell variable

The API key may be retrieved directly from the app accessible on the Publish > Apps page. It can also be retrieved via Apigee API call.

• In the Cloud Shell SSH session, run the following command:

  export PROJECT_ID=$(gcloud config list --format 'value(core.project)'); echo "PROJECT_ID=${PROJECT_ID}" export API_KEY=$(curl -q -s -H "Authorization: Bearer $(gcloud auth print-access-token)" -X GET "https://apigee.googleapis.com/v1/organizations/${PROJECT_ID}/developers/joe@example.com/apps/retail-app" | jq --raw-output '.credentials[0].consumerKey'); echo "export API_KEY=${API_KEY}" >> ~/.bashrc; echo "API_KEY=${API_KEY}"

  This command retrieves a Google Cloud access token for the logged-in user, sending it as a Bearer token to the Apigee API call. It retrieves the retail-app app details as a JSON response, which is parsed by jq to retrieve the app's key. That key is then put into the API_KEY environment variable, and the export command is concatenated onto the .bashrc file which runs automatically when starting a the SSH session.

  Note: If you run the command and it shows API_KEY=null, the runtime instance is probably not yet available.

Test the API

1. Retrieve the categories as JSON using this curl command:

   curl -k -H "apikey: ${API_KEY}" -X GET "https://eval.example.com/retail/v1/categories"

   This verifies that, by default, the API will return a JSON payload.

2. Retrieve the categories as XML:

   curl -k -H "apikey: ${API_KEY}" -H "Accept: application/xml" -X GET "https://eval.example.com/retail/v1/categories"

   This verifies that you can use an Accept header to request an XML response. The returned fields have the same values as returned in JSON.

Congratulations!

In this lab, you converted JSON to XML in response to a request by the client.

End your lab

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