About developing with portal services
The ArcGIS REST API also allows you to work with users, groups, and items from ArcGIS Online or an internally deployed portal created with Portal for ArcGIS. You can build web, mobile, and desktop applications that support sharing and collaboration using web maps. You can also use the API to publish hosted services to ArcGIS Online or your own portal.
Portals allow users and organizations to publish and share content over the web. ArcGIS Online and its ArcGIS.com website constitute an example of a portal. A portal has users, groups, and content. Users can be part of an organization or unaffiliated with an organization. Users sign in to the portal and create and share content items such as web maps. The system supports maps, layers, applications, tools, and data files. Users can choose to keep content private, meaning it is only accessible to them, or shared. Shared items are accessible to groups or the public (everyone).
A portal supports different types of maps, layers, applications, tools, and data files. Each item has a type, such as web map (type of map) or feature service (type of layer), and a set of type keywords that provide additional information on the characteristics of the type. Items are classified as maps, layers, tools, applications, and data files based on the primary use of the item.
Items may be classified into two broad type categories based on their reach: web content and desktop content. Web content is actively consumed across all client platforms, including web browsers, mobile devices, tablets, and desktops. Desktop content is primarily consumed by desktop applications and needs to published as geospatial web services before it can be widely consumed over the web. The portal can be used to store and share this content among users who can download the content and use it locally. Web and mobile applications that work with content including the ArcGIS.com website have the option of only presenting web-accessible content by default.
Security is based on the ArcGIS Online sharing model. Items are only accessible to users and groups with which the item has been explicitly shared. By default, an item added to the system is private and only accessible to the user that added the item. It is not available to others; for example, it does not appear in search results and is not part of any group. User and application identity is determined via an authentication process that requires credentials. Application developers are encouraged to use the Identity Manager from the client SDK they are working with to manage the authentication process.