The scenario is that users of web application can purchase digital items. The web application will use Paypal Instant Payment Notification.
The IPN protocol consists of three steps:
PayPal sends your IPN listener a message that notifies you of the event
Your listener sends the complete unaltered message back to PayPal; the message must contain the same fields in the same order and be encoded in the same way as the original message
PayPal sends a single word back, which is either VERIFIED if the message originated with PayPal or INVALID if there is any discrepancy with what was originally sent.
Let's say it's VERIFIED, how could I know who have completed the transaction or purchased the item (user of the web application) if the user used other email address in his/her paypal? I have stored the email address of the user in session but what if he/she have different paypal email? Paypal email is included in IPN message.
For other details, maybe not useful, the application is written in Struts2 in Google-App-Engine.
You'll need a way to correlate the IPN data coming back with the user. Either by asking them to provide their paypal email or using the username/password generation facility in the IPN service. Here is a somewhat inelegant but functional approach:
When the IPN comes in off the wire, persist the paypal generated username/password and payer_id (in perhaps the datastore).
If you can't correlate by email, then when the user comes back to your site request that they enter the username/password generated from paypal's site once (just to correlate).
Lookup the username/password and then correlate their userid from the UserService back to the payerid.
The reason to use IPN is for subscription services as you can get IPN messages when the subscription is terminated, cancelled, or when payments come in (for an account that stopped paying).
The most important thing to think about is how to correlate a user of your site back to the payer_id (or even payer_ids in some cases) that are used to pay for the services they are using.
On another note, I wouldn't use the session to store information for IPN callbacks, those actually can take a LONG time sometimes (say when the x.com conference is on and everyone is hammering paypal).
If you have a running application or a better description of the look & feel, I might be able to come up with a more elegant suggestion. Let me know if this helps at all.
Why don't you use PayPal's express checkout? This way you negotiate server2server a token and then you can check with PayPal the result of that token on user's return.
If users are buying directly from your application it's easier to implement.
And I think it'is more robust than the method you're using (I never heard of it before :D )
Related
From my app, I want to use SalesForce APIs to get datas about contacts (first/last name, mobile phone, email).
1/ is it free $ to use SalesForce APIs ?
2/ Where can I have access to the information about this specific API request ?
Many Thanks
"It depends"
You're paying for user license(s) already, in that sense the API requests are free. Accessing the Developer Edition / trailhead playground app is truly free. Then there are things like Essential Edition, Platform Edtion or whatever's the name - there's no API access in them out of the box. API is available in Enterprise, Unlimited etc. You need to check the edition you're planning to connect to.
And then... well, there are rolling 24h limits of API requests. Very forgiving in sandboxes, bit more strict in production (where they increase with every user license you buy or you can purhase extra "bandwidth")
It also depends how will you make these requests. Will you have 1 dedicated integration user or will every user of your web app log in to SF via your app and then you're piggybacking on them in a way (which is useful if your org has complex sharing rules for example and you need to be sure user sees in your app only the data they're allowed to see in core Salesforce).
Which brings us to how to connect. You have SOAP API and REST API. Depending on your programming language there are ready-made connectors for .NET, PHP, Python, Java... Regardless which you choose there will be at least 2 http calls needed. 1 to log in and get session id back, 1 to run actual query.
With SOAP API you pass username & password in login call, get XML message back with session id and endpoint (base url to use from now on). And then you'd query. SELECT FirstName, LastName, MobilePhone, Email FROM Contact or whatever you need.
With REST API there are more options, there's similar username-password flow but there are also more secure ways where your app never sees the user's password, user enters it on SF login screen and is redirected back to you. This is very good if you're making a web app or mobile app. You'd need to read up about all OAuth2 flows available.
Again - there's a chance you can say "don't care" and just use say https://pypi.org/project/simple-salesforce/
I am faced with a rather strange request and there isn't much material online tackling that.
I am building a web app on GAE ... front end, back end, datastore, blob store, user accounts, the whole nine yards ...
Part of the requirements is to have a user communication system, (users sending messages to each other, just like Facebook) as user emails are not to be shared among other users, and the web app shall only send emails to the user sign up email strictly for security and administration purposes, and wont flood their inbox with notifications like some websites do.
I have narrowed narrowed it down to 4 options
Option 1:
Reinvent the wheel - Build this whole system form scratch on the Datastore and Blob store. However, not only is it expensive, but also I am not gonna go through all of that (just saying honestly)
Option 2:
Build a bouncing system ... User A sends message to app ... app bounces email to User B. Not very Elegant, impossible to create threads and conversations, eats up app Mail Quota used for Marketing and what not.
Option 3:
Host My own Email server onsite. Patch an API servlet and run the whole show through API. Very valid, except that the client doesn't want anything on site, and I wont be around to maintain it for him.
Option 4:(Best option if someone helps out)
Implement option 3 on a 3rd party email provider. Which brings us to the question, is there any respectable email provider that allows account sign up through API ?? I need to create a shadow email account on a 3rd party server(that the user will never know it exists) every time someone makes an account on my app. Then store all emails and their generated passwords in the Datastore, and when user logs in my web app, web app logs in 3rd party server, retrieves messages and serves it. When he wants to send a message, web app gets the message, sends an email using API as well. If someone knows how to do that on Gmail, I would be eternally grateful (but I highly doubt google allows that)
Note
I can implement the whole setup on xmpp/Jabber servers as well but these free servers keep changing all the time and they change their configurations ... bottom line they are not very reliable.
Thanks a lot guys !! I really appreciate any feed back and if you have any other suggestions please don't hesitate !! This is by no means a solid plan yet.
I need to integrate PayPal with my client AngularJS app, where the app visitors can donate specific amounts of money based on various causes, but not sure where to start? My client requested that visitors can select cause, amount to be donated, then get routed to Paypal to enter their details, process payment then finally routed back to the app for (thank you page) which should receive payment confirmation as parameter.
I've skimmed through the PayPal developers API and can see that there are a lot of options / features offered but not sure really where to start and which is the best approach to accomplish my client needs? Shall I use REST API? or will simple button integration do the job? What if I need to add causes selected to Paypal checkout page? Can I do this using the API? Thanks
If you don't have some specific reason to use REST I would recommend just going with the Classic API, specifically Express Checkout. It's much more mature and provides a lot more freedom to integrate with different options and customization.
With Express Checkout you'll be using the following calls.
SetExpressCheckout
GetExpressCheckoutDetails
DoExpressCheckoutPayment
You'll call SEC and that will return a token. Then you'll redirect the user to PayPal with that token appended to the URL. The user signs in and approves the payment, and they're returned to a URL that you supply in the SEC request.
At that URL you can call GECD to obtain all the details about the buyer. This allows you to tae their address and apply any shipping or tax rules you need to so that you can present a final review before the user would approve the payment, which is when you trigger DECP to finalize the transaction.
There are various options with that flow. For example, GECD is optional, and depending on your flow you may or may not need a final review, so you could skip straight to DECP and display nothing but a final receipt page when the user gets back to your site if you want to.
If you happen to be using PHP my class library for PayPal will make all of this very simple for you.
So I'm writing a mobile app and have reached a point where I need to allow users to register a username. I'm doing this by asking for an email address, username and password.
Typically, it's been normal to set this sort of thing up on the web by having the user confirm his email address by clicking on a link sent to his inbox.
Needless to say, on a mobile app this is a bit clunky as the user will be redirected out of your app and into his browser.
So I had a look at how other mobile apps are doing it (WP7) and was surprised to see that DropBox and Evernote both allow you to sign up without confirming your email address. The end result of this is that I was able to sign up with completely bogus email addresses and/or valid email addresses that don't belong to me.
I assume this is done on purpose.
Your thoughts?
I came across the same issue when writing a social networking style app. I chose to have the user create a username and then provide and email and password. I do not verify the email address and I've never attempted to send any email to them (yet).
What I would suggest would be alternate ways to validate a users email address. My app allows users to do Facebook Connect. All they have to do is log into Facebook, and the app talks to Facebook to confirm that they are using a valid email address. No need to verify it with a URL in an email.
I believe Twitter has a similar service and there may even be a few others that provide an API.
I've also discovered that a lot of people just want to tinker around in the app and not create an account at all. It's definitely a balancing act
I'd say it depends on your app and how important it is to ensure users have valid email addresses. In an app I'm creating now, we want to discourage users from signing up with multiple bogus accounts (because our system could be gamed that way) so we're not allowing users to log in until their email address if verified. On other sites however, it might not be such a big deal so why bother users with that extra step?
As for a mobile device, I don't see why you can't still send a verification email that sends them to your website to verify their email address. There are plenty of mobile apps that also have a website users can log into to manage their account.
Another option is have multiple "states" for users. Before they validate their email, they are in a "pending" state. Once they click it, they're in an "active" state. If you store the createDate for the user, you can periodically remove pending users older than 1 week (or however long).
The bonus is that you can easily add more states, such as suspended or deleted.
Personally, I wasn't too happy for users to create accounts with any old email address.
I think a few decent options are:
send a confirmation email with a link that uses a Custom Url Schema to redirect back to the app (although this is only good if they use the link on the same device)
send a short PIN in the email for them to enter back in the app.
send a confirmation email with a web link, have your server confirm the valid email/token, and have your app check the account status either periodically or with some sort of realtime tech like SignalR or Firebase.
I prefer the last one, although hardest to implement. A user might well have their phone in their hand and their laptop next to them, register in the app and try to click the link in the email that just showed up on their laptop. I like the idea of the app then just "knowing" that they've validated.
Do you have a web server? Write a web service that does the validation for you on the server side, and sends back the result.
Either you can use some platform, such as Facebook connect as #Brian replied above, or you may give users a reasonable timeframe to verify, for example, a few days or even a week. After that, the account gets removed.
You can even have your app issue notifications to remind the user to verify his account (such as every day, or on the last date of the verification.
Don't ask for email confirmation on mobile and allow the user to use the service. When the user is using a PC, then ask the user to confirm his email.
I won't defend my recommendation because most of the solutions here are valid. There isn't one correct way. You asked for ideas and here's one.
A good strategy is to allow people to use as much of your app as possible given the amount of data they've provided.
For example, in the case of a newsreader you might let someone browse your app without registering, then require an account for offline syncing, and a verified email for alerts. Always give people a good reason to take the next step, and build engagement first, then people will forgive you pestering them later.
What is the best practice to handle transaction between application and paypal.
Consider:
I'm Alice and I want send money to Bob
In my DB I see that Bob has $200 and I want to send him $150.
Once transaction is sent I want to update the Bob's account such that it would contain $50.
Now according to PayPal API I can send Pay and receive success. However what happens
if I for example send Pay it succeeds but I fail to receive a response due to network problem. So I assume that error happened and try again and technically I'll send $300 to Bob instead of $150?
How can I handle such a transaction - between a local database that keeps an account and the remote PayPal API?
I had this exact concern recently with an ASP.NET MVC project I was completing for a client.
I learned two things:
Communication between Paypal and your database cannot be trusted (well, didn't really learn this, but it was entirely reinforced)
I now understand why so many websites that have Paypal as a transaction type mention there could be a processing period between the time that the transaction was completed and shipping/delivery of the product is completed.
The way you handle the situation is similar to the way a business could handle personal checks:
A personal check looks like currency (and typically is), but many businesses would like some sort of verification from the bank that funds are available before they accept payment - so they use a machine that asks the bank if funds are actually available.
If the machine says the funds are available, the business trusts it and you complete the transaction. However, the machine can give an error message that typically means "the funds are not available or something went wrong" and the business has a decision to make:
We can trust the customer and accept the check, deliver the product, and hope for the best when later depositing the check to the bank.
Or we can tell the customer that it will take time for the check to clear, deposit the check, wait for the funds to actually arrive in our account, and (if successful) deliver the product after the business receives funding.
This sounds inefficient with the way many businesses operate today, but it is something that does come up. In fact, this is why a lot of businesses stray away from accepting personal checks, they are unreliable when compared to other methods of payment.
Now how does this correlate to handling a Paypal payment?
A Paypal payment looks like currency (and it typically is), but many businesses would like some sort of verification from the Paypal that funds are available before they accept payment - so they use Paypal PDT, IPN, or other method for checking that the transaction was handled appropriately.
If Paypal properly responds to one of the verification requests, the business can trust it and complete the transaction. However, your website may throw an error of some sort (i.e. Paypal could reply with an IPN response of NOTVALID, or you could never get a reply from Paypal). The business has a decision to make:
The business can trust the customer and accept that they have made a Paypal payment and everything should be alright (very bad decision in the case of a Paypal transaction)
Or the business can tell the customer at check-out time that there may be a 72 hour processing period for Paypal payments.
This may not sound like the best way to operate your business, but it is the way we have to deal with an imperfect internet.
I would set up the Paypal payment flow similar to this:
UserA wants to send $100 to another UserB using Paypal
UserA enters the value in the 'checkout field' and is sent over to Paypal to verify the transaction.
UserA is sent back to your website from Paypal and your website performs the IPN check with the details that Paypal has POSTed to your site(I chose IPN in this case - as if we were using Express Checkout as opposed to some other payment gateway that Paypal offers).
If the IPN is VALID, process the transaction as expected.
If the IPN is not VALID, mention to the customer that there may be a delay in processing, have your application send you a notification that a possible Paypal transaction issue has occurred (you may want to include a reference id so that you can quickly find which transaction this notification is referencing), and mark the transaction as pending as opposed to complete or something similar.
An admin of the site who handles these notifications will manually investigate the transaction (or force the website to check with Paypal again - see the Paypal API documentation for details on this) and manually mark the transaction as complete or failed.
Notify those involved of the status of the transaction.
It is annoying that we have to have extra steps involved to make sure the money was transferred, but, as mentioned earlier, we are using an imperfect system and we want to be very certain of the success / failure of financial transactions.
An added bonus to this process is that there is likely to be notifications when someone is tampering with the Paypal payment system - leaving you better equipped to deal with evil-doers in the future.
Please refer this link ,Hope PayPal Authorization & Capture method will be suitable for you ,since you don't want lose the response as well as miscalculated amount transfers, PayPal provides correlation id that can be referred for PayPal to confirm your order status,it will be better to pass the order id to PayPal API.
https://cms.paypal.com/us/cgi-bin/?cmd=_render-content&content_ID=developer/howto_admin_authcapture
http://www.scribd.com/doc/6303345/40/CorrelationID-for-Reporting-Problems-to-PayPal
Good Luck!
This is known as 2-phase commit. As long as paypal does not participate in the same transaction, you will run into problems.
I would debit Alice the $150 and reflect the transaction is "Pending Confirmation", then periodically poll PayPal to synchronize your DB, since you have no control of when the network or PayPal may be available, post, reverse or adjust the transaction. Once PayPal processes the transaction, you can change the status in your DB from "Pending" to "Completed". BTW, this how bank accounts and credit cards are processed. You could apply a double-entry accounting method to your DB. (see this Q&A)
From what i see you need to make sure the transaction is complete otherwise nothing should be done .
If you deposit the money into PayPal API and you do not receive an response from PAYPAL API then you need to rollback the transaction in you DB.