What is access token in Facebook API?
why I need it ?
What is its purpose ?
Do I need to store it persistently in my website ?
For almost every request you make to facebook API you need to pass access token along to get the results. This token may expire depending on what kind it is, you might need to persist it in case your application need to access facebook API when user is offline.
PS: Access token comes from user's request to your application.
Facebook implementation of the OAuth 2.0 involves three different steps: user authentication, app authorization and app authentication. User authentication ensures that the user is who they say they are. App authorization ensures that the user knows exactly what data and capabilities they are providing to your app. App authentication ensures that the user is giving their information to your app and not someone else. Once these steps are complete, your app is issued an user access token that you enables you to access the user's information and take actions on their behalf.
access token will be expired unless the user has granted to your app the "offline_access" permission. In other word, unless you have such a perm granted, you don't need to store it persistently in your website.
Related
Question: Is it possible for application which associated with business manager to obtain ads_management permissions and make server-to-server calls using appId|appSecret as access token.
If yes then what are the correct steps to obtain those permissions for an app?
If no then is there a way to get access token for the user with such permissions which never expires?
Details: As stated in FB documentation, in order to make server-to-server requests without need to obtain and refresh access tokens we may use pair of app Id and app secret in form of appId|appSecret.
Our application now has the following permissions:
- email
- public_profile
- user_friends
In order to make calls to Ads API our application has to have ads_management permissions. Currently we make calls to Ads API through user-level access token and this is not preferable for us as this token requires refreshes which must be done manually using browser interaction (we can't obtain access token programmatically)
You may be confusing App Access Tokens (which allow you to make calls on behalf of the app itself) with permissions (which an individual user grants you to act on their behalf) - you'll always need a user token to update things belonging to a user.
A user, who's an admin of the ad account you want to manage, needs to grant your app ads_management permission - once they've done that, the OAuth flow gives you an access token to make API calls on their behalf, and that token doesn't expire for up to 60 days (after which point they need to come back to your site/app while logged into Facebook for you to get an updated token)
In the context of Business Manager, that user must be someone that has access via Business Manager to the assets (ad acccounts and pages) you want to update via the API
If your app has Standard access to the Ads API, you can also use 'System Users' to make sessionless API calls to update the assets of the business: https://developers.facebook.com/docs/marketing-api/businessmanager/systemuser/v2.2
More info about login here:
https://developers.facebook.com/docs/marketing-api/guides/chapter-1-Setup-and-Authentication
https://developers.facebook.com/docs/facebook-login/access-tokens
Each user who allow permission to my app will have an access token
or
One access token can handle actions, for example, upload photos to an user album?
I know that an access token can expire up to 60 days,
so do I need save this access token for each user on my database and when request comes from that user, load the access token for him?
Each user who allow the app will have an access token, which will include all the permissions user has granted to your app.Read more about user access tokens here
Each user who allow permission to fb app, will have different Access Token which will be unique.
The Access Token is generated on the basis of browser session from client, AppID and App Secret. In a web server based application, it is not absolute requirement to save application token for user. But application like HootSuite saves user credentials and access token for later use to get facebook feeds and other services.
So it depends on application requirement.
Thanks
Each user sends you another access token in context to use User session of course.
An access token is a random string that provides temporary, secure
access to Facebook APIs.
A token identifies a User, App or Page session and provides
information about granted permissions.
And in User Access context:
You can use this token to perform API calls on behalf of a user,
including reading, publishing and deleting, depending on the
permissions your app has. For example, you can retrieve a user's
friend list or publish a new photo to their timeline with a user
access token.
http://developers.facebook.com/docs/concepts/login/access-tokens-and-types/
Yes, you have to remember this access token if you dont want to reconstruct it. But in many API's this is done "automagically", for e.x. in PHP SDK the access token is stored in user cookie. If you implement more complicated user-flow, you have to remember access token OR regenerate it each time (http://developers.facebook.com/docs/concepts/login/login-architecture/). Remember, that access token will expire and you will have to regenerate it (on the faith of already granted permissions).
FYI: If you want to preserver offline access (executing application activities without user session), you will consider offline_access, but it is deprecated:
http://developers.facebook.com/roadmap/offline-access-removal/
Hope it revealed the problem.
On my app the user can sign to Facebook and the app then has the user's access token (say it's 'abc'), I want to use this token to create a user on my own server.
Is it safe to send this access token to my server (using SSL), then get the user's username and ID using https://graph.facebook.com/me?access_token=abc on my server and check that the application the token belongs to is mine with https://graph.facebook.com/app?access_token=abc. If it is my application I then store the user in my user's database and/or log them in.
Can this system be fooled? Can you think of a way someone could log in as someone else?
You should check out all of the Authentication documentation and the Oauth spec to see the different auth flows available
Broadly speaking, you can create a user on your server based on the access token, and be reasonably certain that when you get an access token from Facebook for the same user ID that it's the same person.
If you require very high security for the app you can take steps to ensure the user's access token wasn't produced via malware or the Facebook user being tricked, there's an example showing protection against CSRF in the Server Side Authentication documentation, and there's also a reauthentication flow you can use
I assume that you are using facebook sdk for this, if so the facebook sdk takes care of the security for you and you don't have to worry about a thing.Supposing that you are accessing the api without the sdk then there are two things that must be noted:
1) Auth token expires frequently(facebook has taken great pains to ensure that the user is protected)
2)Making a request with just auth token is not enough there are some other parameters that are needed that can't be faked especially if you are doing this server side since an extra layer is added that fb calls server flow authentication
3)On top of that there are a lot of permissions that are in place that the user has to give in order for an application to access some data.The link below provides a nice article on authentication you can take a look
https://developers.facebook.com/docs/authentication/
So long story short it is safe.
I wonder is it possible to access user's wall info without passing his/her access token?
for example, I will just pass my app secret token and app id. and FB user already allows to access his/her info from my app. Facebook does the checking and matching of my app and my app's user by just using my app secret token and app id.
Because I found some topics similar to that.
http://forum.developers.facebook.net/viewtopic.php?pid=9172
When I check Rest FB doc,it says like that.
http://restfb.com/javadoc/index.html
public DefaultFacebookClient()
Creates a Facebook Graph API client with no access token.
Without an access token, you can view and search public graph data but can't do much else.
I doubt that it will work or not without access token.
can everyone share me ideas or any possible similar approaches ?
Thanks.
You will need to ask the users to authorize your app for offline access. You will be able to access the user's wall even if the user is offline, but you still need the access token. It is part of Facebook's security measures.
There are two types of access tokens:
Session based: expires in a short term, are used when the user will be logged to FB every time you need to perform an operation.
Offline access: do not expire and allow the app to perform operations for the user in any moment. This requires the offline_access permission when the app is authorized.
Check here: http://developers.facebook.com/docs/authentication/ for the oauth mechanism and here: http://developers.facebook.com/docs/authentication/permissions/ for the permissions list.
The REST API is deprecated and it is strongly suggested that you don't use it anymore. Furthermore, from this October you will be allowed to use only the Oauth2 authentication (see When is Facebook turning off their session based auth?)
Without token you can only access public information.
Public data
From RestFB homepage :
// It's also possible to create a client that can only access
// publicly-visible data - no access token required.
FacebookClient publicOnlyFacebookClient = new DefaultFacebookClient();
If the user does not protect his posts, then you can access everything without token. But most of user do protect their data and then you need a valid user access token to read the data.
Private data
When you say "FB user already allows to access his/her info from my app" it means that the user has clicked on "Allow app" in the web browser and at that moment here Facebook will give you a token. You can after use that token with RestFB :
FacebookClient facebookClient = new DefaultFacebookClient(USER_ACCESS_TOKEN);
User user = facebookClient.fetchObject("me", User.class);
out.println("User name: " + user.getName());
By default, the token will expire a few hours later. If you ask for the offline_access permission, the token will be valid for ever (as long as the user does not remove the permission for your app in his settings). You should store that token in your database to be able to use it when you need.
Get the user token
You cannot get the user token with RestFB. On the RestFB homepage, you can read :
Non-goals: [...] Providing a mechanism for obtaining session keys or OAuth access tokens
Because you need a browser to do so : the user has to authenticate and authorize your app on Facebook website (the popup that shows).
What you can do is to have a PHP page on which your users have to go to authorize your app. You can read this stackoverflow answer that explains how to use the Facebook PHP SDK to do so.
Hope that helps !
Facebook changed their Graph API recently to require an access token. Therefore I quickly made a Facebook application to be able to retrieve an access token, use a URL similar to the one below, generated my access token and implemented the token in my iPhone application. Lately I have been thinking about if I have done something wrong. Should I request the access token everytime a user of my application retrieves data from the Graph API? I am starting to doubt whether or not the access token is unique to each user or just to the Facebook application.
Can I hardcode an access token into my application or should I make a request on the URL below every time I need to retrieve data through the Graph API?
I am generating my access token with the following URL:
https://graph.facebook.com/oauth/access_token?client_id=MYID&client_secret=*MY_SECRET*&grant_type=client_credentials
Access token granted by user have expiration time. If token expired then you need to request it again. But if you ask user to grant you "offline_access" permissions then you'll have almost not limited access token. You can store it in database or file and use next time.
Here FB documentation about permissions:
http://developers.facebook.com/docs/authentication/permissions/
Enables your app to perform authorized
requests on behalf of the user at any
time. By default, most access tokens
expire after a short time period to
ensure applications only make requests
on behalf of the user when the are
actively using the application. This
permission makes the access token
returned by our OAuth endpoint
long-lived.