Teaching Tableau Server - Part Four
Welcome back to my guide to getting you through the Tableau Server Qualified Associate exam. We're making great progress, having gone through all of the pre-installation steps, and we've installed the Tableau Server software.
The next steps are to set up all of the permissions on the server; but we're going to pause and take a closer look at the processes that comprise Tableau Server, how they interact with each other and what their functions are. Having a basic knowledge is a requirement of the QA exam.
I've included a screenshot (below) of the processes at work in a multi-node environment. As we know, for the purposes of the QA exam we need only to concentrate on single machine deployments. So, let's go through the processes in the order below and give you enough information about them to answer the QA exam questions.
This process is installed by default and is responsible for monitoring various components, detecting failures and executing failover where needed. There is only one cluster controller per machine.
This is an Apache web server component whose role is to handle requests to the server from all clients — Tableau Desktop, mobile devices, a proxy, a load balancer, etc. It listens for requests coming in on port 80 (or port 443 for SSL requests) The server runs a single instance of the gateway process; you can't run more than one per machine.
The Application Server handles the web application (the web UI that your Tableau Server users access). It also handles browsing, searching and REST API calls.
This is where the magic happens... The VizQL server is responsible for loading and rendering all the views on Tableau Server. This process is usually highly used, therefore multiple instances per machine are the norm.
You'll remember that on set-up we had to decide how often to refresh our cache, the default being "Refresh Less Often". Well, this is the service that hosts the cache and serves up the content to users when it has a copy of what they want, rather then questing and rendering it again through VizQL.
Search & Browse
This service handles fast search, filter retrieval and display of content metadata on the server.
Backgrounder is another workhorse of the Tableau Server - particularly if you're a heavy user of Data Extracts. This service executes server tasks such as extract refreshes, subscriptions, "Run Now" tasks and tasks initiated from tabcmd. Because it handles many requests you can have multiple backgrounders running on your server - and indeed have they spread across multiple servers.
The Tableau Data Server lets you centrally manage and store Tableau data sources. It also maintains metadata from Tableau Desktop, such as calculations, definitions, and groups.
When working with extracts, Data Engine is the key component responsible for loading, querying and servicing end user requests for visualisations. It is the component that loads extracts into memory and performs queries against them.
The repository is the Tableau Server database. It stores workbook and user metadata.
So, there's our whistlestop tour of Tableau Server processes. Sadly this is stuff that you're just going to have to remember as the exam is a closed book exercise. From personal experience I did get a question of server processes, so brush up on them!
Keep an eye out for the next instalment when i'll guide you through working with the server, setting up sites, groups and permissions.