08 Apr Microsoft Teams different components and logical architecture
Microsoft Teams different components and logical architecture
Recently many people requested information on Teams different components and how these components work together to deliver Teams different capabilities. So, this is the motivation for me to write this blog post. This post based on the details available on Microsoft documents and details shared on events.
Let’s start with basic details, and then Teams building block details and their connectivity. Microsoft Teams is unified communication and collaboration tool which deliver multiple features which requires for teamwork. Popular features such as persistent chat, optimal 1:1 and group audio/ Video call, online meeting with desktop sharing, file sharing, Team and channel and so on. These all features are coming different Teams service inside the Microsoft 365 cloud. It is important to understand how these different services working.
As figure 1 shows, Architecture perspective what Microsoft Teams brings together Office 365 services and intelligent communications (intelligent communications are the Skype next-generation service). Microsoft 365 Core Services such as exchange online, SharePoint, OneNote, Office 365 apps and intelligent communication cloud are the component of the architecture that enables all communication capabilities including persistent chat, meetings and audio/video calls. Then Teams has Teams service shown in figure 1, and Teams services are the services that the Microsoft engineering team build to creates Microsoft Teams. It orchestrates the layer that brings together all the other pieces. For example, attaching Office 365 group to team, when you create one for easy membership management.
In many cases, Teams client not only sits on the top of the Teams layer but also Teams client is more efficient because it directly talks to the office 365 services thats’ why they go across.
Figure 1 Teams high-level architecture 
What is the Intelligent Communications Cloud?
You may think, what Intelligent Communications cloud is, and what does it consist of? Intelligent Communication Cloud is formerly known as Skype next-generation service; that’s where the messaging, calling and meeting service, People, configuration, and identity service reside. These are all next-generation evolution of Skype services that Teams uses for messaging and voice over IP (VoIP) calling. Intelligent Communication Cloud where the PSTN telephone network integration system is, and that’s also used for Skype for Business Online stack. Another critical service is a unified presence for Teams and Skype for Business Online. These different services showed in figure 2.
Figure 2 Microsoft Teams next-generation services 
Note: There is no unified presence between Microsoft Teams and Skype for Business On-premise.
Microsoft Office 365 services used by Teams:
In Figure 3 shows on the right-hand side are application services such as OneNote, PowerApps, Planner, PowerPoint, Word, excel. In figure the left-hand side shows the platform services including Exchange for email and calendar in Teams is same as Outlook calendar, Teams uses graph to retrieve calendar, Modern group also known as Office 365 group, SharePoint for content collaboration, Stream for voice recording, OneDrive for Business for file sharing and Information protection provides the shield for these services. The bottom part shows Power BI for data analytics.
Figure 3. Office 365 services and Teams
Microsoft Teams capabilities and their data store locations
As supporting Teams users, frequently get a question from our users that where is my Teams data stored, such as conversation (chat), files that user shared, images, and many more. Teams chat persistent, which means it stored entirely, and it uses its storage. Group chat and One-to-one chat is stored in Cosmos DB, and channel conversation is going to store in cosmos DB as well as per Microsoft . Teams also keep a copy of all chat messages in exchange that is mainly to enable information protection.
There are two scenarios, includes user have a one-to-one chat or group chat. Teams do a copy of that chat into the mailbox of the individual people who are part of that chat. If you chat in channel teams, keep a copy of that chat in the mailbox of the Office 365 group that is attached to that team.
Specific to the file, Teams leverage OneDrive for Business and SharePoint for file storing in Teams. There are two scenarios as shown in figure 4, file shared with one-to-one chat is stored on OneDrive for Business and permission automatically granted by teams for the user who needs the access. Another scenario is when a file shared between channels. Then Teams will upload that file to the SharePoint team site that gets created when that Team created and the file permission automatically granted to every member of that Team. This is important for content collaboration [7a].
Where the users voicemail stores? Voicemail is another critical feature that most of the enterprise users utilize voicemail stores in exchange mailbox of the user who receives a voicemail, as similar to Skype for Business. Not only voicemail but calendars and Teams contact also stored in exchange.
Where are users meeting recording stores? Whenever the user records a meeting that first stores in the same media storage where images stored, then the recording will be encoded and made available on Microsoft stream for content collaboration. Within 24 hours, teams will purge the recording from media store to Microsoft stream so that the user can share their meeting recordings with others.
The Teams telemetry stores in Microsoft Data warehouse without any customer content such as email address and contact number.
Figure 4 Teams activity and data storage place 
Note: Data in Teams resides in the geographic region associated with your Office 365 tenant. Currently, Microsoft Teams supports Australia, Canada, France, India, Japan, South Africa, South Korea, United Kingdom, Americas, APAC, and EMEA regions.
Now you understand how many components involved in Teams architecture, the next important question comes from a technical community that, how do Microsoft Teams intermingle with Office 365 technologies?
Microsoft Teams logical architecture:
In figure 1, you saw Teams different components and how they communicate with each other. In figure 5 demonstrates Teams logical architecture, Teams client is the interface to access Teams service in real-time communication and collaboration for teams.  Teams connector provides a novel way to integrate third-party (apps published by third-party) apps.
Figure 5 Teams interaction with underlying services 
Microsoft Office 365 group and Teams tightly integrated. Why is it integrated? For example, when a user creates a Team from an existing Office 365 group, that groups membership, site, mailbox, and notebook if any, are emerged in Teams, in case Office 365 group and teams integration breaks then Office group will not materialize in Teams that is why Office 365 and Teams tightly integrated.
OneDrive for Business – OneDrive for Business mainly used for storing personal user documents until they shared with others. In Teams perspective, when a user shares a file in one to one chat, which is stored on OneDrive for Business and permission automatically granted by teams for the user who needs access.
SharePoint Online – It mainly used to store Team files that shared within channel and team sites. When the Team creates a SharePoint site automatically provisioned, once the file shared within a team, the access permission automatically granted by teams to all team members, so, teams file tab directly interacts with SharePoint Team sites.
Exchange Online – Every Team has a group mailbox, and a team member has an individual user mailbox. Teams meeting scheduled by individual stored on their mailbox and calendar. So, the Teams calendar directly interacts with Exchange online mailbox.
Microsoft Stream – It uses for creating and sharing videos securely. For Teams perspective, all team meeting recordings are stored and shared using stream. Also, Live event (large broadcast event) hosts in Stream. The live event will be cover later in this chapter.
Microsoft Teams depended on Services:
You discover how Teams logical architecture works with Office 365 services. Teams do have specific dependencies with other services such as Team chat features directly interact with chat service in Office 365, One to One chat stores on user mailbox, and group chat stored on teams group mailbox; therefore, the chat is dependent on exchange online . Teams files and wiki dependent on SharePoint Team sites. Teams meeting and call dependent on Skype next generation calling and meeting services, meeting calendar stored on users mailbox, and files (One to One sharing) depended on OneDrive for Business. Refer the figure 6 which shows dependent services.
Figure 6 Teams dependent services.
Note: SharePoint Online is a requirement for using OneDrive for Business. Users cannot store & share files on the channel without SharePoint Online and OneDrive for Business.
 Microsoft Teams architecture update retrieved from https://myignite.techcommunity.microsoft.com/sessions/83471?
 Microsoft Teams logical architecture retrieved from https://docs.microsoft.com/en-us/microsoftteams/teams-architecture-solutions-posters