Document Classification:
Original Document Author:
Software Requirements Specification (SRS)
<Authors name>
Document Title:
Last Revision Date:
SRS to Clone and Change VMs
08/12/2013
Page 1 of 17
Table Of Contents
Table of Contents
Document Revision History
1
Introduction
11
Purpose
12
Document Conventions
13
Intended Audience and Reading Suggestions
14
Product Scope
2
3
4
4
4
4
5
15
References
Overall Description
21
Product Perspective
22
Product Functions
23
User Classes and Characteristics
24
Operating Environment
25
Design and Implementation Constraints
26
User Documentation
27
Assumptions and Dependencies
3
External Interface Requirements
31
User Interfaces
32
Hardware Interfaces
33
Software Interfaces
34
Communications Interfaces
4 System Features
41
User interface SP Website behavior
42
Administrator Approval Process
43
Session Management Platform Integration
44
Application server interaction with VMware Host System
5
Other Nonfunctional Requirements
51
Performance Requirements
52
Safety Requirements
53
Security Requirements
54
Software Quality Attributes
55
Business Rules
5
5
5
6
8
9
10
10
6 Other Requirements
Appendix A: Glossary
Appendix B: Analysis Models
Appendix C: To Be Determined List
17
17
17
17
2
Page 2 of 17
10
11
11
11
11
11
12
12
13
13
14
15
15
15
16
16
17
Document Revision History:
Date
Author
Version
Change Reference
08/12/2013
Govardhan Gunnala
10
No previous document
Page 3 of 17
1. Introduction
1.1 Purpose
This document explains specifications for implementing a new feature for VM
based Citrix Session setups. The new feature is called “ability to clone and
change the VM Citrix Sessions”. This feature is to let customers self update
the base VMs used in VM based Citrix Sessions.
1.2 Document Conventions
This document is organized based on the IEEE Standard for Software
Requirements Specification (SRS) (IEEE 830-1993) and contains the
necessary requirement and some aspects of the analysis of the requirements.
Below are the notations used for representing various sections in the
document
1. Main Sections
-
2. Main Sub-Sections -
Represented in this format
Represented in this format
3. Sub-Section Topics - Represented in this format
1.3 Intended Audience and Reading Suggestions
This document is intended for the anyone in who understands the VM based
Citrix Sessions and working on automating the tasks that are currently
manual.
Product Management: The management who wants to get an idea of what
all the components involved in developing this new feature so as to plan
resources and development activities.
Developer: The developer who is responsible in authoring code to develop
and integrate this feature with existing Session Management platform, must
firstly consult this document to understand the involved technical
requirements so as to find the most suitable technologies for development.
Page 4 of 17
Infrastructure Administrator: The Infrastructure Administrator who is
responsible for provision of infrastructure to host this feature in existing
setup so as to understand what infrastructure requirements are.
1.4 Product Scope
This new feature addition to VM based Citrix Sessions, offers flexibility to
customers to make changes to their base VM images at any time without any
delays. This also reduces the engineering staff efforts in implementing the
changes, which are manual otherwise.
1.5 References
Please refer to below documentation that explains the business requirement:
2. Overall Description
2.1 Product Perspective
This new feature is an addition to the existing Session Management platform
and its infrastructure. This feature reduces the manual efforts from in
making changes to the base VM image whenever customer has to push a
newer version of the software or make any changes to the existing setup.
Thus new feature facilitates a workflow in which customers will be able to
create VMs with required changes and can approve the requested changes
for deployment in live.
Page 5 of 17
2.2 Product Functions
The primary use case: customers would have a web based access to the
base VM images with options to
1. list available base VM images,
2. clone a VM out of chosen base image,
3. login to the cloned VM and make changes to the VM
4. save the modified VM as new a base image or override an existing
base image
5. disregard the changes to the VM
6. create a new Citrix Session setup from updated base image
7. make new Citrix Session setup live
A technical feasibility: test has been performed on VMware technology
that uses for VM based Citrix Sessions. It’s found to be feasible to support
use case requirements by cloning a VM from base image and saving the
changes back to the base image via VMware PowerShell Automation APIs.
The background operations mainly include
1. creating a new VM as a clone of existing VM
2. renaming cloned VM at VMware and Windows System level
3. automatically assigning an IP-address for the new VM
4. enabling RDP access to the new VM as local Administrator
5. auto-login customer to the new VM
6. saving the new VM as base image by setting new name and moving it
to appropriate base images location
7. stop the newly created base image
8. delete the newly created VM
Front-end and back-end workflow integration services: This includes user
facing UI and approval for changes deployment to live
UI: customer facing access is going to be SP (Support Portal) whose
interface would re-used for this new feature provision to the customers.
As existing SP runs on IIS web site, the new feature pages and code will also
be deployed to the same web site.
Page 6 of 17
The respective IIS pages would provide below options:
1. list of customer specific base VM images
2. option to select base image from the list
3. right click context menu with options “Convert to Active VM”
4. list of customer created active VMs
5. right click context menu with options
 Launch RDP to the server
 Convert to base Image
 Discard the active VM
6. create a new Citrix Session setup
7. make new Citrix Session setup live
Approval: An approval process by staff is required to
1. validate the requests from customers and
2. avoid unnecessary entries creation by customers
3. keep setup in well managed and controlled state
4. ensure needed infrastructure is in-place to accept the user request
A designated staff would receive a request for approval via email whenever
user chooses to
1. save an Active VM as base Image – staff would verify the required
resources are in-place and ensure not too many base images are
created
2. create a new Citrix Session setup – staff would verify that required
Session Management platform changes are in-place to support
sessions. Customer would verify the application in session via TD
sessions before to approve it for live.
3. make new Citrix Session setup live – staff would make required
customer/vanity URL changes to point them to the new TD sessions
and retires the previous setup
Session Management Platform Integration: When user selects option
to “create a new Citrix Session setup” a new distributed app will be created
with all settings same as its existing setup except that it uses new base
image with a new Dev URL. The designated staff would verify the auto
created distributed app Session Management setup and then approves the
request.
When user selects option to “make new Citrix Session setup live”, will
ensure the proper URL setup for both customer using and Vanity URLs and
then will also retire the previously existing setup.
Page 7 of 17
High Level Technical Architecture Diagram of New Feature Integration
2.3 User Classes and Characteristics
VM Citrix Session Customer (ISV):
Each ISV as a customer will have a single login to SP. They can login to SP
from anywhere via SP website. Upon login they will be presented with a
section that will take them to the VMs Citrix Sessions. Customer will be able
to operate with right click context menu to perform VM based operations.
Once customer is through with test quick from new VM Citrix Session
session, a request for live approval can be placed.
VM Citrix Sessions
administrator:
A designated team of staff will form a VM Citrix Sessions administrators list.
There will be an administrator account per ISV for staff to manage the
customer requests. The group will have an email list to which all of the
customers’ requests will be sent. Upon a user request, admins can login as
respective ISV admin account, do the approvals as appropriate.
Page 8 of 17
2.4 Operating Environment
The new feature will be available via SP web site. All of the operations that
either an end user/admin performs will be translated into respective VMware
PowerCLI API commands via web page code. The commands will be sent to
Application server which would have VMware PowerCLI software installed and
thus executes these commands.
The PowerCLI commands in turn connects to VMware vCenter server,
executes the commands and returns the results.
The typical environment for this whole functionality includes
1. VM HOST: is a Physical server that runs VMware ESXi Hypervisor
2. VMs & Guest OS: a set of VMs that are loaded in Citrix Session
sessions for end users. Currently supported VM guest OS is Windows
Server operating systems usually 2008 R2 editions
3. vCenter server: is a Management system to interact with VMware host
to execute VM operations. This will be installed on a Windows Server
system. The version of vCenter to be used depends on version of ESXi
4. Application servers: A Windows server system (usually 2008 R2) on
which agent software is installed and configured successfully.
VMware PowerCLI API software as well will be installed on this server.
Optionally it can run VMware vSphere client software which is required
to work with vCenter server for any troubleshooting.
5. Session Management Management Server: is the centralized system
that manages all of Application servers running the Agent software.
This server will be utilized for session management on Application
servers
6. Session Management Database server: is a SQL database server
hosting the database for Session Management platform.
7. Session Management Web Servers: Windows servers with IIS installed
and hosting the SP web site. usually be located in DMZ behind the
firewall.
8. Active Directory server: is a Windows directory services server that
authenticates the users logging into the SP portal.
9. Firewall: is a Windows server system running Cisco firewall software
with defined access rules. This lets access only to the allowed
resources on network for external world.
10. SP Website: accessible from anywhere for all (internal/external) of the
users, built and runs on top of IIS website. Can be accessed via any of
the browser software.
Page 9 of 17
2.5 Design and Implementation Constraints
The new feature primarily relies on clone functionality of the VMware
software. For support of VM clone operation one needs to run a vCenter
server of version respective to their VM host ESXi.
The feasibility evaluation is performed on latest version of ESXi and vCenter
software that is v5.1.0, if you have ESXi hosts running older version verify
that all of feature needed PowerCLI commands are working.
2.6 User Documentation
Here are the official links to the VMware Technologies and Automation
resources:
VMware ® vCenter Server
VMware vSphere PowerCLI Overview
Product Support for VMware vSphere Hypervisor (ESXi)
2.7 Assumptions and Dependencies
It is assumed that SP website will be acting as user interface to present the
new Feature and its options. If not, a similar web site with basic functionality
to authenticate user against AD and interacts with Session Management
Management & Application server to send commands, receive command
results and present to user, has to be developed.
For creating cloned VMs, user would provide a name for the VM and the same
name would be used as the guest Windows system name. It’s assumed that
the cloned VMs would be running in the same network as of other active VMs
running the TD sessions. In such a network there would be a DHCP/auto IPaddress assignment configuration in place.
It’s also assumed that communication interfaces required for user facing SP
website would pre-setup and there doesn’t require any specific changes for
this new feature.
It’s also assumed that there would be an email communication channel that
can be used for notifications to Admin accordingly to user actions.
Page 10 of 17
3. External Interface Requirements
3.1 User Interfaces







SP Login page: used by external user and/or internal admins
For VM based Citrix Session customers, a separate page to manage
their VM images would be provided
For the customer login, there will be list of context menu options that
he can perform against list of VMs displayed
For specific approval needed operations, an email notification would be
sent to VMs admin list
For Admin user login, there would be list of VMs along with customer
requests that are pending for approval. Admin user can approve or
decline the request.
Once a dependent operation is approved, user can move on to the
next operations
In case of any failure/error messages, customer would log a request
with via same SP portal under his current logon session
3.2 Hardware Interfaces
The new feature is based on VMs in which most of the hardware resource as
well are found and configured at the VM Host level.
3.3 Software Interfaces
The new feature functionality connects to vCenter server via VMware
PowerCLI API installed on application servers. PowerCLI API supports
triggering command remotely. To let uses to work on cloned VMs, a RDP
session to the VM will be used.
3.4 Communications Interfaces
SP is a web solution which would require HTTP access through firewall to the
respective web server for external users to launch the website. The backend
operations would need TCP/IP communication from Application servers to
the vCenter server. Solution needs RDP access from Application servers to
the Windows systems running in the VMs.
Page 11 of 17
4. System Features
4.1
User interface CPP Website behavior
A1
Login to SP
 ISV user login from external network

ISV Admin login from internal network
A2
User verification: authenticate the logon credentials provided
against Active Directory to validate the user
A2.1
If authentication fails, report login failed.
A3
For successful login, show below options:
A3.1
For ISV user login
 find the list of VM based applications for the ISV from
Session Management console DB and present a page the
list of VM applications.
 for selected VM based application, get the list of application
VM base images and Active VMs from DB and present the
list
 for selected VM base image, present following right click
context menu options
A3.1.1
Right click context menu options on a selected VM base image
 Convert to Active VM
A3.1.2
Right




A3.2
For ISV Admin login
 find the list of pending requests for approval and show
them against the application in the list
 for selected request, provide options to Approve or
Disapprove
A3.2.1
If there are no pending requests, default the view to that of ISV
user login
click context menu options on a selected active VM
Login to the server
Create new Citrix Session
Convert to Base Image
Delete
Page 12 of 17
4.2
B1
Administrator Approval Process
VM based Citrix Session Administrators list would be notified with
email for below customer actions:
 Convert to Base Image
 Create new Citrix Session
B2
In case of “Convert to Base Image” option: administrator needs to
follow below steps
 If user chooses to replace the existing image by specifying the
same name, move the previous base image to a periodic
backup location
 Ensures there are not any other stale VM images lying around
 Login to the SP portal and approves the request
B3
In case of “Create new Citrix Session” option: administrator needs to
follow below steps
 Verify the respective distributed app got successfully created in
Session Management console
 Review the setup and update the server name/IP-address with
the active VM that user chosen
 Ensure that networking and RDP access are properly set for
that active VM
 Login to the SP portal and approve the request
 Once approved a test link to the new distributed will be sent to
the customer for verifying the changes in TD session
4.3
Session Management Platform Integration
C1
When user chooses “Create new Citrix Session” option, a new
distributed app would be created by copying the existing VM based
TD app from the Session Management Management server via a
script/code execution
C2
Once the admin approves the “Create new Citrix Session” request,
Session Management will start forming VM based TD sessions from
the assigned App server
C3
Customer verifies the new VM changes in Citrix Session sessions
Page 13 of 17
created via new Citrix Session distributed app
4.4 Application server interaction with VMware Host System
D1
TD VM Session Management Application server will receive the
commands corresponding to the user action and makes connection
to the VMware vCenter server that manages the VMware host
system
D2
On selected base image, for user action Convert to Active VM: below
sequence of PowerCLI commands will be performed:
1. Read-Host: Prompt user for a name to the cloned VM
2. New-VM: with chosen base image as source VM to clone
3. Start-VM: Will bring the cloned VM into Active state
4. Rename windows: Run WMIC/Registry commands to change
the Windows System name to avoid conflicts on the network
5. Restart-VMGuest: Restart VM in order for Windows system
rename action to take affect
D3
On selected Active VM, user can perform following operations:
D3.1
Login to the server:, below sequence of PowerCLI commands will
be performed:
1. Guest.IPAddress: Retrieve the IP-address of the VM selected
2. Create .RDP file with IP-address of the VM and along with
default Admin credentials. OR alternatively rely of MSRDP
ActiveX code and create respective files for selected VM.
3. Launch RDP session with auto-login
D3.2
Create new Citrix Session: below sequence of commands will be
performed:
1. Run a script/code on the Session Management Management
server that creates a new DistributedApp which is a copy of
existing one.
2. Sends a user request email notification to
administrators list
3. Follow the admin approval steps defined in section: B3
Page 14 of 17
D3.3
Convert to Base Image: below sequence of commands will be
performed:
1. Read-Host: Prompt user for a name to the base Image
2. If the new name is same as existing one, prompt for
confirmation to replace exist
3. Follow admin approval process steps defined in section: B2
4. Set-VM: rename the VM with new name provided for Image
5. Stop-VM: This will poweroff the VM as base Images do not
run actively
D3.4
Delete: below sequence of commands will be performed
1. Stop-VM: This will poweroff the Active VM
2. Remove-VM: This will delete the VM and its files
5. Other Nonfunctional Requirements
5.1 Performance Requirements
For the major portion performance is linked primarily to website loading and
backend VM operations. To ensure faster VM operations setup will include a
decent datacenter hardware for both VM host and vCenter servers. Further to
that VM density for VM host has to match the ratio of hardware resources vs.
allocated VM resources.
The key backend operation cloning a VM usually takes around 5-10 mins for
per VM of size 20 GB from base image. The speed of this and other
operations directly depends on VM host hardware.
5.2 Safety Requirements
The new feature backend operations will not affect other applications
installed on application servers. However, enough care should be taken on
the backend VM host resource monitoring so as to avoid any broken
operation unnecessarily occupying resources on it.
Page 15 of 17
Consistency: To ensure smooth VM operations, conversion from active VM is
not recommended. Whenever user requests to convert from active VM to
base image, system should first shutdown the active VM and then do the
conversion tasks.
5.3 Security Requirements
The new feature will be available via SP website for only VM based Citrix
Session customers. SP website acts as front end layer handling the user
authentication against AD and communicating to resources from proper
firewall access.
In SP each customer (ISV) will have one user login and there will be only one
respective ISV admin login for purposes. This single login user/admin per
customer ensures the right audience access and avoids conflicts due to
simultaneous access otherwise.
5.4 Software Quality Attributes
Reliability:
Use of VMware technologies for backend VMs hosting and its automation is
an industry leading option with proven reliability across the businesses.
Involved VMware automation interface provides relevant error messages in
case of any exceptions while executing the commands. These should be
translated to appropriate message to interact with customer operating in SP
website.
Maintainability:
approval procedure plays major role in ensuring the quality of setup
before accepting user requests for approval. This includes verifying and
ensuring allocation of proper VM host resource, cleaning up old/stale VMs
and its resources, etc., The approval workflow will have SLAs to be met to
keep customer informed with availability of their changes they requested.
Availability:
Using SP, customer can report any failures for support which will follow
support channel defined for addressing the SP user’s requests.
Page 16 of 17
Integration with Session Management platform ensures that end users
sessions will be serviced only for successful session creation.
5.5 Business Rules
1. New feature development should be designed with usability as the first
priority. Keep detailed exception handling for faster support
resolutions.
2. Follow fine tuned SLAs in approval process and ensure faster
responses to customer
3. Review and plan Hardware/Software requirements including licenses
periodically
6.
7.
8.
9.
Other Requirements
Appendix A: Glossary
Appendix B: Analysis Models
Appendix C: To Be Determined List
Page 17 of 17