Kaizen #24 - CORS and the JS SDK

Kaizen #24 - CORS and the JS SDK

Hello everyone!
Welcome back to another week of Kaizen!
In this post, we will discuss the Cross-Origin Resource Sharing (CORS), and how it is used in Zoho CRM's JS SDK.

What is CORS?
Cross-Origin Resource Sharing (CORS) is a mechanism that uses additional HTTP headers in requests to allow web apps running in origin A, access to selected resources in origin B.
The below image depicts how CORS requests are served in a browser.


Here, in a web document hosted in domain-a.com, the main page, the layout CSS, and the image is served from the same domain (domain-a.com), while the canvas image is served from a different domain (domain-b.com). 
Therefore, the request to fetch the canvas image from domain-b.com is a cross-origin request controlled by CORS.

What requests use CORS?
  • Invocations of the XMLHttpRequest (XHR).
  • Web fonts so that servers can deploy TrueType fonts that can only be cross-site loaded and used by web sites that are permitted to do so.
  • Images/video frames drawn to a canvas using drawImage().
  • CSS shapes from images.

CORS Request Types
The browser decides the request type based on the request methods (GET/PUT/POST/DELETE) and the request headers.
The two types of CORS requests are
  1. Simple Requests
  2. Pre-flight requests
1. Simple Requests
  1. The browser sends the header ORIGIN in the XHR (XMLHttpRequest) to inform the target site about the request's origin.
  2. On the target site, the server compares the ORIGIN value with the allowed origins.
  3. If the source is allowed, the target site allows access to the resource to the requested site. Otherwise, the request is denied.

2. Pre-flight Requests
Before the actual request is sent, a pre-flight request is sent to the target site.
  1. The browser sends the pre-flight request via the OPTIONS HTTP request method.
  2. The server sends the details about the target site such as the allowed methods and the allowed origins.
  3. After deciding whether the target site could return the requested information based on this response, the browser makes the actual GET/POST/PUT/DELETE request.

Therefore, the server must send back the header Access-Control-Allow-Origin in the response header to serve simple and pre-flight requests appropriately.

Access-Control-Allow-Origin : [origin]
Example : Access-Control-Allow-Origin: https://www.example.com
This header allows only the website mentioned here to access the resources.
Here, https://www.example.com can access the resource on the target site, since it is explicitly allowed.
The server compares this value to the one sent in the ORIGIN header of the request, and accepts/rejects the request accordingly.

Access-Control-Allow-Origin : *
Example : Access-Control-Allow-Origin: *
The wildcard character (*) means that any site can access the resource in the target site. This practice is unsafe and hence, not widely used.

CORS and Zoho CRM JS SDK
Zoho CRM's JS SDK contains methods to invoke Zoho CRM's APIs that are CORS-enabled. All you have to do is register your JS app in Zoho Accounts Developer console  and authenticate it. 
You can then just use the methods available in our JS SDK in your code, and make API calls to Zoho CRM.

Prerequisites
  1. Your app must have the redirect.html page to which the access token is sent.
  2. The redirect.html page must contain the script to save the tokens in local storage based on the parameters sent after user authentication.
Before you can use the CRM APIs, you must
      a.  Register your app
      b. Authenticate your app

a. Register your app
  1. Go to https://api-console.zoho.com.
  2. Click ADD CLIENT
  3. Choose the client as Java Script and click CREATE NOW.
  4. Specify the client name, homepage URL of your app's UI, redirect URI (the HTML page of your application where you want the users to be redirected to after providing consent to your app), and the JavaScript domain.
  5. Click CREATE.
  6. Your client ID, client secret will be displayed under the Client Secret tab.

b. Authenticate your app
  1. Call the authorization URL from your HTML app.
    https://accounts.zoho.com/oauth/v2/auth?scope={scope}&client_id={client_id}&response_type=token&state=zohocrmclient&redirect_uri={path_to_the_redirect.html_of_your_app}
  2. Provide the necessary scopes, and the redirect_uri.
  3. The Zoho Accounts page prompts for user credentials. The user enters the credentials and may grant access for the entire session. 
  4. After the user grants access, Zoho Accounts redirects the user to the page you specified in the redirect_uri. You can see the access_token, grant_for_session as parameters to the redirect uri in the address bar.
    Example: javascriptDomainName/redirect.html?access_token={access_token}&grant_for_session=true|false
  5. The redirect.html file must run the script to store the access token of a particular user in local storage and use it while making API calls to Zoho CRM. This file is available in the attached ZIP of this post.
  6. Parse the access_token parameter to obtain the OAuth token.
  7. Note that the OAuthtoken expires every one hour. Generate a new one as and when required.

Note
  • You can find the sample JS app as an attachment to this post.
  • You can also download our JS SDK from the Github page.

After you download the ZIP, it opens the jssdktest folder that contains the below folders.
  • app - This folder contains the redirect.html file which holds the script to store and retrieve tokens from local storage.
  • index.html - The HTML file that renders the form where the user-entered details are captured to insert a lead in Zoho CRM. This file also calls the init() method to simultaneously initialize the SDK while the user submits the form.
  • js - this folder contains the zcrmsdk.js and the processData.js files. 
    zcrmsdk.js holds all the API methods.
    The processData.js file contains the script to initialize the SDK (init()), the action that happens when the user clicks the Submit button on the web page (submitData()) etc,.

Let us now see how CORS works while using the JS app.

Step - 1: User Redirection and SDK Initialization
The user visits your web page and the app redirects the user to Zoho Accounts with the client id, scopes, and the redirect URI that you have specified in the processData.js file.



The user enters the Zoho Credentials. Zoho Accounts prompts for user consent.
When the user clicks Accept, Zoho Accounts redirects the user to the URL you specified while registering your app. In our case, it is the path to the redirect.html file inside the app folder.
This step simultaneously initializes the SDK and runs the script to store the token.

Step - 2: redirect.html runs the script to store the access token
After the user grants access to the app, the access token is sent as a parameter in the address bar of the redirect URI.
The redirect.html invokes the setAccessToken() method and stores the token in local storage.
Here's the code snippet.

function setAccessToken() {
        var hashProps = getPropertiesFromURL();
        if(hashProps) {
            for( var k in hashProps) {
                if( hashProps.hasOwnProperty(k)) {
                    var key = ( k === 'access_toke' || k === 'access_token' ) ? 'access_token' : k;
                    var value = ( k === 'api_domain' ) ? decodeURIComponent(hashProps[k]) : hashProps[k];
                    localStorage.setItem(key, value);
                }
            }
        }
        setTimeout(function() { window.close(); }, 0);
    }
    setAccessToken();
You can also see the access token in the browser console under the Application tab.



Step-3: Display the Homepage of the app (index.html)
After the access token is obtained, the index.html page (the homepage URL you specified while registering) of your app is displayed.
The user enters the details in the form and clicks Submit.



Step-4: Invoke the submitData() method from the processData.js file
Clicking the Submit button invokes the submitData() method that contains the code to insert the lead in Zoho CRM with the details furnished in the form.
The code snippet is as follows.

function submitData()
{
    var firstName = document.getElementById("firstName").value;
    var lastName = document.getElementById("lastName").value;
    var email = document.getElementById("email").value;
    var company = document.getElementById("company").value;

    var dataObj = {'First_Name': firstName,'Last_Name': lastName, 'Email': email, 'Company': company};
    var input = {'module':'Leads', 'body':{'data':[dataObj]}};
        headers = {'Content-Type': 'application/json'};
       ZCRM.API.RECORDS.post(input).then(function(resp){
                var jsonData = JSON.parse(resp);
           window.location.replace(window.location.origin + "/view.html");
     //location.reload();
        });
}

Step-5: Make the cross-origin request to insert the lead
The method submitData() sets the headers and makes a function call to ZCRM.API.Records.post() which in turn, makes a CORS request to the Zoho CRM server.
You can see the request headers being set in the browser console under the Network tab.



As you can see, the header Access-Control-Allow-Origin contains the value as the JavaScript Domain.
When this domain and the one specified during app registration matches, the request goes through and the lead is inserted in CRM. Otherwise, the app receives the error.
Below is the screenshot after the lead is inserted in CRM.



The major advantage of using the JS SDK is that all APIs are available as JS functions,  and CORS code handling is already done. All you have to do is incorporate the requested methods in your app's code and make calls from the registered JavaScript domain.


We hope you found this post useful. Stay tuned for more!

Cheers!














    Access your files securely from anywhere

          Zoho Developer Community




                                    Zoho Desk Resources

                                    • Desk Community Learning Series


                                    • Digest


                                    • Functions


                                    • Meetups


                                    • Kbase


                                    • Resources


                                    • Glossary


                                    • Desk Marketplace


                                    • MVP Corner


                                    • Word of the Day



                                        Zoho Marketing Automation


                                                Manage your brands on social media



                                                      Zoho TeamInbox Resources

                                                        Zoho DataPrep Resources



                                                          Zoho CRM Plus Resources

                                                            Zoho Books Resources


                                                              Zoho Subscriptions Resources

                                                                Zoho Projects Resources


                                                                  Zoho Sprints Resources


                                                                    Qntrl Resources


                                                                      Zoho Creator Resources



                                                                          Zoho Campaigns Resources


                                                                            Zoho CRM Resources

                                                                            • CRM Community Learning Series

                                                                              CRM Community Learning Series


                                                                            • Kaizen

                                                                              Kaizen

                                                                            • Functions

                                                                              Functions

                                                                            • Meetups

                                                                              Meetups

                                                                            • Kbase

                                                                              Kbase

                                                                            • Resources

                                                                              Resources

                                                                            • Digest

                                                                              Digest

                                                                            • CRM Marketplace

                                                                              CRM Marketplace

                                                                            • MVP Corner

                                                                              MVP Corner





                                                                                Design. Discuss. Deliver.

                                                                                Create visually engaging stories with Zoho Show.

                                                                                Get Started Now


                                                                                  Zoho Show Resources


                                                                                    Zoho Writer Writer

                                                                                    Get Started. Write Away!

                                                                                    Writer is a powerful online word processor, designed for collaborative work.

                                                                                      Zoho CRM コンテンツ






                                                                                        Nederlandse Hulpbronnen


                                                                                            ご検討中の方





                                                                                                  • Recent Topics

                                                                                                  • Chart View group X-axis values above a value

                                                                                                    I have a data set with X values ranging from 0 up to 300-400, the Y values are an AVG of the values for the given X. I am interested in the values at the low end of the scale, say 0-10 and want the X values 10 and greater to be grouped into a single category
                                                                                                  • How do I get the Text Account name instead of the Reference number?

                                                                                                    Good Morning everyone! I am very new to zoho analytics. I'm trying to create some pivot tables and when I add the Account or Division name it comes up as a reference number. From my research, I need to use a lookup. I'm having a really hard time understanding
                                                                                                  • Custom API - Need to create a string return value, not only MAP

                                                                                                    @Support: When creating a Custom API it only allows a return from a function of MAP type. The service I'm using requires a string return, how can this be achieved?
                                                                                                  • missing video-urgent

                                                                                                    hi..I have a problem regarding zoho meeting. I already record almost 2hrs for my interview session. After end my session, i'm stop the recording. Its happened when i didn't received any meeting recording at my email.But i received recording 7minutes after
                                                                                                  • Duplicate New Ticket Emails

                                                                                                    I am getting two Ticket emails when a ticket is created. The first one goes to me as the Admin helpdesk@ And because I am an Agent as well it also send to helpdesk@, support1@ and support2@ Is there any way to stop this?
                                                                                                  • Ticket Response Email Template

                                                                                                    Is there a way to have an email template automatically selected when I click on Reply for a ticket?
                                                                                                  • Unpublishing Job Post for LinkedIn

                                                                                                    Hi, We have experienced issue with the above. We did unpublish a job in Recruit but it still appear under Job section in our LinkedIn page. It did not remove from LinkedIn as it should be.  Please check and advise. Regards, Snyder 
                                                                                                  • Power of Automation :: Automatically start / pause / stop timer on task status update.

                                                                                                    Hello Everyone, A Custom function is a user-written set of code to achieve a specific requirement. Set the required conditions needed as when to trigger using the Workflow rules (be it Tasks / Project) and associate the custom function to it. Requirement:-
                                                                                                  • Editor limitations to define screen types

                                                                                                    Guys I have noticed that even in version 2.0 of the editor (which is this new one we use) we still have a lot to improve... When I compare to some more global solutions like Wix, Zyro, Go Daddy, Squarespace and Weebly feel that we have some limitations
                                                                                                  • Dúvidas do Zoho Creator

                                                                                                    Pessoal, Estou colocando um tópico para dúvidas do Zoho Creator. Um abraço, Leandro
                                                                                                  • Tropicalize Books

                                                                                                    Books is an incredibly powerful tool that works well in many countries. But I feel that it is a product that is not yet "tropicalized" for Brazil as we speak (this would be like adapting the local reality). We have many strong competitors who do more
                                                                                                  • Automatic Sitemap Generation

                                                                                                    Guys are all right? Doesn't make sense for me to have to generate a map site and upload it... because it's not automatically generated just as it is done in WIX? where the customer doesn’t have to worry about this.
                                                                                                  • SEO improvements with ZIA

                                                                                                    Are you okay? I would like to bring an idea that would be amazing to improve the product that is the possibility of being able to improve the SEO of the pages (this of each page or each article on the blog) through ZIA so that it could create page Summary
                                                                                                  • Automatically updating field(s) of lookup module

                                                                                                    I have a lookup field, which also pulls through the Status field from the linked record. When the lookup is first done, the Status is pulled through - this works perfectly. If that Status is later updated, the lookup field does not update as well. As
                                                                                                  • Initiating a SalesIQ Zobot from a custom button on Zoho Sites

                                                                                                    I have created a Zobot set to initiate on a custom action called "Fast_Answers". On Zoho Sites, I created a code snippet button and set it to on-click run the event called "Fast_Answers". I installed the SalesIQ integration code into the Zoho Sites Page
                                                                                                  • Zoho Desk -> Zoho Analytics : Where is the field for "Layout" ?

                                                                                                    I have many different layouts on my helpdesks and I want to be able to identify the stats for each one, however I can not file the field in the raw data from the Zoho Desk datasource. I thought it might be under "Tickets" but there is nothing. There is
                                                                                                  • Set resolution mandatory field

                                                                                                    Hi,  i have 2 questions:) : - i want to set the resolution field mandatory before close the ticket. Because for now, i can close the ticket without writing how i solve it - how can i setup zoho desk to receive ticket by email(e.g. clients sent email to support@mydomain.com) and it create a ticket in zoho desk
                                                                                                  • Impuesto automatico en cotizaciones

                                                                                                    Buen dia Mi pregunta es como se puede poner alguna operacion para que las cotizaciones me salgan automaticamente con impuestos ya que uno al cargarla al final tienen que añadir el porcentaje de impuesto Saludos
                                                                                                  • Zoho Assist "Agree and Download" Button "Greyed Out" ("Light Blued" Out)

                                                                                                    Anyone else having issue where support clients are unable to click "Agree and Download" to access the client so that we can provide remote support? This is for "on demand" support via accessing the support page and entering the support key and name. This
                                                                                                  • Project Billing with the Staff Hours Method in Zoho Projects

                                                                                                    The Staff Hours Billing Method in Zoho Projects allows you to bill your clients based on the actual time spent by each team member on a project, at the rate set for each user. This is useful for projects where different skill sets are needed and service
                                                                                                  • Creator Subform to CRM Subform

                                                                                                    Hello all, Has anyone successfully written data from a Creator Subform into CRM subform? I have been able to get the rows to populate but none of the data will come through. I'll add my code and the result in CRM. Creator Subform is 'Delivery_Receiving_Hours'.
                                                                                                  • custom fields not populating from deluge script into invoice

                                                                                                    Hello, I've created some Deluge script that is meant to take a few inputted invoice custom fields and calculate a few others. I can see when I execute the function that my inputted custom fields are being passed, yet im still ending up with all "null"
                                                                                                  • tax summation function - getting error

                                                                                                    Hello, I'm trying to create a function that adds all of individual tax rates from a few jurisdictions. I'm getting an error on line 9 - Value is empty and 'get' function cannot be applied. I've checked that I have data in each of the required fields,
                                                                                                  • Backstage / Zoho Books integration

                                                                                                    Hello. We have Zoho One and have slowly started using Backstage. Loving it. Problem is, we have ZERO accounting control over what is sold through this product. When will we be able to connect it to our existing Zoho Books tenant? Thank you very much!
                                                                                                  • Getting list of calendar events over api for zoho mail calendar

                                                                                                    Hi, I am using just Zoho mail without using Zoho CRM. I wanted to get all events booked in my zoho mail calendar through an api at regular intervals. I could find such API support for Zoho CRM calendar but not for zoho mail calendar. Can you kindly let
                                                                                                  • Allocate emails to user in a shared mailbox

                                                                                                    Hi, This might be obvious, but I cannot find the answer. I have 3 shared mailboxes so any team member can see the emails. Is there a way of allocating a specific email to a user so that it is their responsibility to deal with it? Thanks in advance.
                                                                                                  • Introducing Zoho Campaigns' own gateway for SMS campaigns

                                                                                                    We are excited to announce the launch of our SMS Gateway to send SMS through Zoho Campaigns. We have also made a few other changes in our current SMS Campaign model to improve your over all user experience. These updates are planned with an aim to expand
                                                                                                  • Update a lookup field in CRM from Creator using deluge

                                                                                                    I have a Creator form that creates a new account. When it creates the new account in the Accounts Module, I need it to also populate the Parent Account, which is a lookup field coming from the Module Parent Accounts, field Parent Account Name. I have
                                                                                                  • SMS Keyword Tracking in Zoho CRM From Zoho Campaigns

                                                                                                    Is there a way to track SMS leads in campaigns by associating them with specific keywords or codes? Additionally, can these leads be pushed to the CRM while retaining the keyword for tracking and reporting purposes?
                                                                                                  • Projects Multiselect API

                                                                                                    Having troubles setting a mutli select field via API. updateMap = map(); updateMap.put("UDF_MULTI1","picklist_id1,picklist_id2"); updateProjectRes = invokeurl [ url :"https://projects.zoho.com/restapi/portal/XXXX/projects/" + projectID + "/" type :POST
                                                                                                  • Bill quantity received / PO quantity

                                                                                                    PO's are raised & often the quantity received is greater than the PO quantity, so when we receive the bill & adjust the quantity on the bill we get.... Quantity recorded cannot be more than quantity ordered. This necessitates the adjustment of the PO
                                                                                                  • ZOHO BOOKS - RECEIVING MORE ITEMS THAN ORDERED

                                                                                                    Hello, When trying to enter a vendor's bill that contains items with bigger quantity than ordered in the PO (it happens quite often) - The system would not let us save the bill and show this error: "Quantity recorded cannot be more than quantity ordered." 
                                                                                                  • Adding Bluesky channel

                                                                                                    Hello, Is Bluesky (AT protocol) soon added on Social ? Bluesky is being developped and is now open to anyone (no more invitation) Thank you
                                                                                                  • Using Queries with dynamic parameters in Kiosk Studio

                                                                                                    Hi, I'm pretty new when it comes to developing within Zoho (I'm really a .NET developer), as it was just added to my responsibilities. For a new feature in the CRM, I'm trying to develop a Kiosk function to show a list of records (retrieved by the new
                                                                                                  • Unused items should not count into the available number of custom fields

                                                                                                    Hey, I realized that unused Items reduce the number of available custom fields. I can't see a case where that makes sense. Especially in our case where we have two different layouts in Deals with a lot of different fields, this causes problems.
                                                                                                  • Introducing Bot Filtering for Accurate Email Campaign Analytics

                                                                                                    Dear Marketers, We're excited to announce a new feature designed to enhance the accuracy of your email campaign analytics: bot filtering. This feature helps you filter out bot-generated opens and clicks, ensuring your campaign reports reflect genuine
                                                                                                  • Tip 37: Time Log Restriction in Zoho Projects

                                                                                                    Timesheet in Zoho Projects helps you big time in entering log hours for the tasks and issues and approving them. Now, with the new Time Log Restriction option, you can set daily and weekly log hour limits. You can restrict users from entering extra log hours than the permissible limit. The limits are restricted to 24 hours per day and 168 hours per week by default based on business hours. To customize, navigate to Task & Timesheet settings under Portal Configuration in Zoho Projects setup and enable
                                                                                                  • Chart showing schedule

                                                                                                    I want to be able to create a chart for everyday to check and which of which driver is available on the timeframe. Here's my table Name City Day Start Time End Time Driver1 Medicine Hat Monday 11:45 AM 4:45 PM Driver 2 Medicine Hat Tuesday 11:00 AM 7:00
                                                                                                  • Multiple Vendor SKUs

                                                                                                    One of the big concerns we have with ZOHO Inventory is lack of Vendor Skus like many other inventory software packages offer. Being able to have multiple vendor skus for the same product would be HUGE! It would populate the appropriate vendor Sku for
                                                                                                  • In Zoho Projects, is there a way to create a folders template under documents that can be used once a project is created?

                                                                                                    We have a specific folder structure that we would like to use that is standard across every project. Instead of having to create this structure every time a project is created, is there a way to create a template for the folders that can be added?
                                                                                                  • Next Page