Simply way to get an idea on SharePoint 2013 apps

Apps in SharePoint 2013:

An app for SharePoint is a web application that is registered with SharePoint using an app manifest and  An app manifest is an XML file that declares the basic properties of the app along with where the app will run and what to do when the app is started.

App Model: The new app model will give us the opportunity to extend our SharePoint system with custom coding. Earlier models support Sandbox solutions and in 2013 we have both Sandbox and App models. 


What is the need of providing separate domain and url's for apps:
We should configure an isolated app domain to create and deploy SharePoint-hosted apps. The main use of providing separate domain and url's for the apps are "To prevent unauthorized access to user data and to reduce the possibility of cross-site scripting attacks". So to enable users to install and use apps for SharePoint in their sites, you must configure your environment to support them.
The apps have their own, isolated URLs, which are separate from the URLs of the sites where the app is being deployed to and where the app is being used. Each installation of an app has its own unique URL within the app domain.

Syntax: http://[app prefix][app hash].[app domain]/[relative site url]/[app name]
e.g:

·         http://Apps-12345678ABCDEF.ContosoApps.com/sites/SiteName/App1Name/Pages/Home.aspx

·         https://Apps-3456789BCDEFG.ContosoApps.com/sites/SiteName/WebName/App2Name/Default.aspx

Best reference to configure the app domain:
http://technet.microsoft.com/en-us/library/fp161236%28v=office.15%29

Apps Services:

• Subscription Settings service.
• App Management service applications service.

You must be running the Subscription Settings and App Management service applications to use apps for SharePoint. These services support apps in your environment by storing the data needed to run apps in the farm. The Subscription Settings service and the App Management Service store app licenses, app principals, app users, app registrations, and so on.

Development tools for apps:

• Visual studio 2012: App for SharePoint 2013, App for Office 365[download from here ]
• Napa tool for Office365 development [Should create the “Developer site” first to add Napa tool for Office 365 development].
• SharePoint Designer 2013 and Visio 2013.

After you install Visual Studio 2012, download and install the Office Developer Tools for Visual Studio 2012 and the SharePoint Client Components, which contain tools and assemblies that you need to do app for SharePoint development
[Download:http://msdn.microsoft.com/en-us/office/apps/fp123627]

Should create a “Developer site” to work on apps in office365/SharePoint2013 because Office 365/SharePoint2013 provisions a separate web site solely for deploying and testing called developer site. You aren’t allowed to deploy your app to any other site in Office 365. The “Developer Site” is a new site template available in SharePoint 2013. No idea now on SharePoint designer 2013 and Visio 2013. Will update once get.

Note: You can only deploy apps for SharePoint from Visual Studio 2012 to a Developer Site.

Where are apps for SharePoint/Office365 hosted?

There are several options for hosting apps for SharePoint/Office365.

• Provider Hosted
• Auto Hosted (Windows Azure autohosted)
• SharePoint Hosted

Where can we host Apps?
1. SharePoint Store
SharePoint Store is owned and hosted by Microsoft. Developers can develop the custom apps around the world and can submit to SharePoint Store. So that any user can be able to download and install them. They can purchase apps if it is not free and buy licenses etc.

2. App Catalog
App Catalog is specific to any organization, where the apps are developed and owned by specific organization. It can be either on on-premises or SharePoint online hosted.

Why server object model avoided in SharePoint 2013 apps?

 With previous versions of SharePoint, farm administrators sometimes refused to install any custom SharePoint extensions because of the danger of errant code. In SharePoint 2013, that problem is essentially eliminated because the client object models have been greatly expanded. This means that you as a developer do not have to use the server object model anymore. 

All your custom business logic moves "up" to the cloud or "down" to a client machine and it uses one of the client APIs discussed in an earlier section. Because the app does not (actually cannot) contain custom code that executes on the SharePoint servers, administrators are assured of its safety.

Some APIs in the SharePoint server object model are not available in the client object models. These are almost entirely administrative and security-related classes.

 

How to configure the App Domain:

http://sharepointchick.com/archive/2012/07/29/setting-up-your-app-domain-for-sharepoint-2013.aspx

Some highlighted points about on apps from MSDN:

1. The “Cloud App Model” is introduced in SharePoint 2013 to build the custom apps.
2. The new Cloud App Model enables us to create Apps. Apps will be accessed from "Site Contents" page.
3. Apps are essentially web applications and build an app for SharePoint is same as build a web application and easy way to add functionality to a SharePoint sites.
4. Apps have it's own site collections and stores all of data there only.
5. Should setup SharePoint 2013 environment to work on SharePoint apps and also you must set up a Domain Name Services (DNS) domain name to provide a host name for the installed SharePoint apps.
6. Use of separate domain is to prevent unauthorized access to user data and to reduce the possibility of cross-site scripting attacks.
7. Create separate URL for the SharePoint apps. Why means the use of separate URLs for apps for SharePoint and SharePoint sites is called app isolation.
8. Note: Each instance of an app for SharePoint that is installed has its own URL. Therefore, if you only have one app for SharePoint in your environment, but the app is installed on six different sites, then you will have six different app URLs.
9. Only SharePoint 2013 supports the SharePoint App Model. You can't build and host apps in prior versions of SharePoint.
10. We can use any language such as HTML, JavaScript, PHP, .Net etc. to build the apps for SharePoint.
11. The Cloud App Model handles the 3tier architecture means in which the app's business logic, data, and user interface (UI) can be distributed into separate components.
12. You can connect your app with just about any internal or public web services, take advantage of the new OAuth 2.0 support in SharePoint, and use the Representational State Transfer (REST) and client APIs (JavaScript and .NET) to integrate and connect your app with SharePoint.
13. SharePoint 2013 app features have web scoped only.
14. SharePoint 203 we have app parts like webparts. App parts runs in Iframe by using click jack technique.