This ServiceNow tutorial gives you an overview and talks about the fundamentals of ServiceNow.
What Is Servicenow??
This opening Servicenow tutorial picks out the most significant foundations of ServiceNow, starting from the bottom up. Understanding the fundamentals of the ServiceNow platform is important. It gives insight into the concepts that underpin how everything else works.
An instance is several things. It is a URL (something like https://.service-now.com/); it’s software running in the cloud; it’s your copy of the ServiceNow platform.
ServiceNow provides a platform and suite of applications as a service. They worry about the hardware, Internet connectivity, and operating system security and provide you with the URL. All you need to get going is a web browser.
An instance is an independent implementation of ServiceNow. It is isolated and autonomous, meaning your instance is not shared with other customers. ServiceNow uses a single-tenancy architecture, which means your instance is yours: you can do what you want with it, such as changing logic, updating the UI, and adding fields.
Every customer has several instances; again, all isolated and independent. One instance might be marked out for developing on, another for testing, and one for production. And, because each instance is independent, each one can be running a different release of ServiceNow. The production instance only differs because it has more powerful hardware.
Changing ServiceNow instance
A new instance starts with a few ServiceNow applications, some demo configuration, and example data. This is often called the out-of-the-box state. One of the example data elements is the System Administrator user. You are able to log in and get going, getting full control immediately.
Everyone makes changes to their instance. Unless the people who will be using the system are called Beth Anglin or David Dan (some of the default example users), you’ll need to load some users at the very least. Some ServiceNow customers configure a lot and some do the bare minimum. You can choose how much you wish to do. Because it is single-tenant, you can alter the configuration and data in almost any way you see fit.
All ServiceNow functionalities are delivered as plugins. When an instance is turned on, one of its first tasks is to load all the plugins that are turned on out of the box. There are quite a few of those, over 200 in the Eureka version of ServiceNow. And there are several hundred more that you can turn on if you want. A plugin may provide an app, like Human Resources Management, or provide new platform functionality, like Domain Separation. Each new version of ServiceNow brings new plugins and updates to existing ones.
When a plugin is turned on, all the data and configuration that the application needs is loaded into the database, meaning that it is ready for work in just a few moments. Many also contain demo data, giving you examples of how it could work.
Servicenow Hosted Instance
A ServiceNow-hosted instance is split over two physical datacenters, a high-availability pair. Each location runs independently of the other, giving a semiclustered environment. In the event of a catastrophic disaster, with one location being completely unavailable, the other nodes will just pick up the load, with almost no downtime. In fact, the process of switching between locations is used for maintenance procedures, enabling your instance to be well-protected against hardware and other failures.
When you visit your instance, you are directed through several layers:
• By looking up the DNS records, you are directed to the currently active datacenter
• The load balancer, by reading a cookie, directs you to the application server you have your session with
• If you aren’t logged in, you get directed to the least-busy application server
• Your application server then uses the database currently determined as active
Knowing The Nodes
From an architecture perspective, a ServiceNow instance is made up of several application and database servers or nodes. These are generally running on shared hardware, meaning that although your instance is logically separate and independent, it is physically hosted alongside another customer. At each location, there are generally at least two application nodes, each running a copy of the ServiceNow platform, which work together to share load. Additionally, there may be worker nodes installed to process the non-interactive jobs, such as event processing. Even though you’ll never directly log in to these worker nodes, they perform some background processing, allowing the interactive application servers to respond more quickly to user requests. For example, a worker instance might send out e-mails or deal with integrations. While there are generally lots of application nodes, there is only one active database server, running on a separate physical server. It does have a redundant pair hosted in the remote datacenter.
Exploring The Database
Once you logged into an instance we can see database records.
You may not realize it, but the homepage, the reports, and the menus to the left are all database records:
Almost everything in ServiceNow is an entry in a database. When you look at the user interface, virtually everything you see—from the data typed in by a user, to log files, to how the views are structured—is stored in the instance’s relational database. Even the scripts you write are kept in a string field in a record, and the files you upload are stored in chunks in the database.
Everything is built on the top of this structure. You don’t need to reboot the server to apply new functionality; you are just updating data records. You don’t need to reload configuration files—any properties you set will be read on the next operation. Even the database metadata, information about the fields themselves, is stored in another table.
This gives you extraordinary control and ability. You can organize, search, and manage the data in an unprecedented manner. You can find scripts the same way you find users, by searching tables. You can control and secure any data, regardless of what it is, by using Access Control Rules. This means you can focus on designing and building great business applications, since the platform works in a consistent manner.
ServiceNow may be considered a high-level platform that is based on the concept of Model-View-Controller. When building a ServiceNow application, you can first think of the data structure. You determine what information you need to store and how it all links together, creating tables and fields. This is the model aspect.
Automatically, you get a simple view on this data, with forms and lists showing your information.
And you can build simple ways to manipulate and change the data, through automation and simple manual updates. This is the controller aspect.
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