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The Sytel Path to
A white paper that focuses on high availability deployment
of the core services within Softdial Contact Center™
Version 1.4 © Sytel Limited Dec 2011 All rights reserved. For distribution to Sytel partners, customers and prospects who are under active
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Table of Contents:1. Introduction ... 1 2. Components ... 1 Softdial CallGem® ... 1
Softdial Campaign Manager™ (CM) ... 1
Softdial Namespace Server™... 2
Softdial Scripter™ (SCR) ... 2
Softdial Publisher™ (PUB) ... 2
Softdial Reporter™ 2 ... 2
Softdial Telephony Gateway™ (STG) ... 2
Softdial Workflow Server™ (SWS) ... 2
Softdial Record Monitor™ ... 2
Softdial Scheduler™ (SCH)... 3
3. Deployment Models ... 3
Core landlord-side Services ... 3
Line-of-business services ... 3
4. Trunk Access ... 4
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S Y T E L | The Sytel Path to Non-Stop Productivity Version 1.4 Dec 2011 1
With Softdial Contact Center™ (SCC) being increasingly adopted as a call center hosting platform, there is a need to dovetail the high availability features of SCC with existing carrier infrastructure for delivering SIP trunk and endpoint capacity to end-users.
For the purposes of this document we will assume that the hosting entity is a carrier, though equally it could be an ITSP or enterprise. We will also assume that the internal network signalling is SIP-based, with RTP carried over a low-bandwidth protocol (G.729). Gateways mediating trunk capacity to TDM support conversion of inband signalling as per RFC2833.
To ensure high availability in a call center SCC has to deliver the following:
1. Automatic and seamless failover of system services.
2. Redundancy measures and load-balancing for gateways delivering trunk access.
3. Dynamic provisioning of all system components.
4. Shared, dynamic configuration store for dial plan, queues, routing, security model and other configuration shared by system services.
SCC is designed from the ground up to deliver these capabilities.
SCC is a suite of services that interoperate using TCP/IP messages over a socket. This set
of services can be deployed over local and wide area networks, on the same host.
Resilience measures are built in at the protocol level, as well as in respect of service behavior.
The components that make up SCC are:
This is a command and control module containing a virtual ACD engine and Sytel’s industry-leading predictive pacing engine. All Softdial services are designed for multi-tenancy from the ground up. CallGem is a landlord-side service and offers up clean logical interfaces for other services and clients. CallGem also acts as a message router.
It also provides load-balancing and
management of gateway interconnection, to manage a series of STG servers as an N+1 redundant cluster. CallGem can reasonably manage 9 gateways (8 + 1 redundant) giving a capacity ceiling of around 4,800 (8 x 600) voice end-points for HMP.
Softdial Campaign Manager™ (CM)
Campaign Manager is Sytel’s data access service. The service is a database proxy that mitigates the need for agent applications to
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S Y T E L | The Sytel Path to Non-Stop Productivity Version 1.4 Dec 2011 2 access a relational database directly. The
single point of data access approach leads to far higher levels of database throughput than with traditional application models. Campaign Manager also provides functionality for managing dialing inventory such as retry management, rescheduling, filters, timezone management, tagging call recordings with line-of-business data. Campaign Manager is a tenant-side service and can be deployed either within the hosting provider’s architecture, or if tenant data security is an issue Campaign Manager can be deployed on the tenant’s site.
Softdial Namespace Server™ (SNS)
The Namespace Server is a configuration store managing hierarchies of configuration data. Configuration is segregated into landlord and tenant data. Tenants can access their own configuration data and perform real-time provisioning.
Softdial Scripter™ (SCR)
Scripter simplifies the task of creating a customized agent application that provides not only agent scripting capability, but is a fully integrated agent desktop call control and management system, that allows even inexperienced users to create, extend and modify such an application. Scripter is a web based application and uses native browser technology with no client side download code, giving advantages in both security and accessibility.
Softdial Publisher™ (PUB)
Softdial Publisher is a flexible data transformation engine that consumes proprietary reporting events generated by dialer and produces reports based on client’s requirements. The versatile Publisher architecture supports a range of client
interface options over TCP/IP or HTTP. It has been designed to ensure high standards of data integrity and data recovery in the event of system failure.
Softdial Reporter™ 2
Softdial Reporter 2 is the latest reporting client that Sytel has introduced in the SCC kit. It is a perfect partner to Publisher, and allows highly configurable data views in either alphanumeric format, or uses one of the over 25 chart formats available. Reporter 2 has a highly configurable and intuitive layout mechanism, giving you ultimate flexibility in arranging your reports on screen, including support for multiple monitors and dashboards.
Softdial Telephony Gateway™ (STG)
Uses host-based media processing capabilities and manages telephony sessions via SIP. The host-based solution can support up to 600 voice end points per host with a dual core processor.
Softdial Workflow Server™ (SWS)
This is a new service from Sytel that allows other applications to treat multi-media sessions as normal call sessions within the contact center. Hence the transition of an agent from handling calls to (say) handling emails or SMS is smooth and requires no special configuration effort. Agents are seamlessly involved in different types of media sessions depending on their access credentials.
Softdial Record Monitor™
Record Monitor allows for instant access to recorded files that are stored in uncompressed WAV format, or compressed MP3 format (using the Lame™ encoder). For efficiently managing the failover scenarios, this service can reside
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S Y T E L | The Sytel Path to Non-Stop Productivity Version 1.4 Dec 2011 3 either on the same host as the STG or a
completely different host on the network.
Softdial Scheduler™ (SCH)
The Scheduler service is responsible for scheduling ACD activity and provides a means to schedule operating system tasks. Typical use of the scheduler is to put queues in and out of service, schedule campaign runs and schedule IVR agent activity. Scheduler can be run both landlord-side and tenant side.
On a standalone premise-based system all of the above services can run on a single host.
This section focuses on high availability deployment of core services in a single site.
The following assumes each server running Softdial services runs a dual NIC configuration and the site runs 2 (or more) separate IP networks to mitigate network device failure.
Core landlord-side Services
(CallGem, Namespace Server, Scheduler) should be deployed in redundant pairs. The simplest configuration is to deploy all 3 services on the same host.
This gives a simple mirror configuration:
In the event that any process fails, it will automatically restart and will be supplied its context by other services that connect to it. In the event of a server failure or access failure, connections will fail over to the mirror server. Configuration is mirrored in real-time and will be correct to the point of failure. This type of failover is managed using the same context mechanism for a single process failure.
Reporting services are deployed on their
own standalone server. This should be done irrespective of the deployment scenario. If using a dual core processor, this server will be able to support at least 250 agents. For redundancy, another server with exact same configuration can be kept as a standby, if the active server fails for some reason. See fig. 2 below.
(Campaign Manager and Scripter) are deployed tenant-side. If these services are hosted, database services need to be
clustered, or at least replicated. There are two options for deploying these services:
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S Y T E L | The Sytel Path to Non-Stop Productivity Version 1.4 Dec 2011 4
Deploy a tenant set of services that is replicated across two servers. It is possible to deploy several instances of these services on the same host. In a traditional server architecture this is how such a deployment might look:
This is a simplified view. In real life one would deploy more tenants per server (10 is typical). At any point in time only half of the services on the machine would be active. The intention is to provide service redundancy without having to make lots of investment in hardware. When planning capacity, one should plan for 2 reasonable-specification dual core servers for each 250 agents – one for database services and another to deliver line-of-business services to tenants.
It is possible to benefit from virtualization if the customer has already made investment in suitable technology. Typically each tenant’s services would be deployed on a single virtual machine. In the event of a failure the VM instance can be
re-provisioned in real-time or a backup virtual copy can be spawned immediately in real time.
Since client access to most of these services is web-based there are standard methods one can use for load-balancing and rerouting of client traffic on failover.
For trunk access, where the carrier has an existing network infrastructure, with a central array of STGs managed by one or more CallGems, the basic configuration is:
In this model the CallGem spreads the load across all available gateways. Bridging between gateways is achieved via SIP calls placed over the LAN, using the G.711 codec to minimize latency.
In the event of a gateway failure, load is redistributed to the remaining gateways. The
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S Y T E L | The Sytel Path to Non-Stop Productivity Version 1.4 Dec 2011 5 possibility to re-establish the lost calls exists
but will be predicated on what infrastructure the carrier has in place to enable this.
In models where the carrier infrastructure has gateways in points of presence, CallGem and STGs can be centralized.
remote site backupThe prescribed topology for remote site backup for disaster recovery is similar to a high-availability scenario. The key difference is that mirroring of core services, reporting services, and backup of line-of-business services, both need to take place over a wide area network. Regardless of technology employed, wide area networks are subject to transient connection failure.
To mitigate this, there are two different ways that service-to-service communication can be enabled within SCC. The default
communication method is a tokenized text string protocol called SDMP (Sytel Dialing Message Protocol). This assumes a reliable connection between the two services. If the connection is broken, resources are deemed to be failed and have to be recovered through the service’s recovery protocols.
SDMP is a terse, low bandwidth protocol, and is full-duplex. It is designed to deliver asynchronous communication between services and clients in as close to real-time as possible. It is, however, a proprietary protocol and therefore not suited for transmission via public access networks.
To deal with this, and the transient issues brought about by having to support remote site backup, it is also possible to carry SDMP messages over HTTP (which can provide robust recovery for temporary connection issues) instead of a permanent TCP connection. There is a lightweight server/ client based process (which can be called as a service wrapper) that sits on top of existing SDMP-based services and performs this re-framing. The most important job that this service wrapper does is to allow for the disconnections that can and will occur when delivering WAN
These service wrappers in general form the basis of a solution to support disaster
recovery. There are several ways in which such a solution can be achieved. Whichever solution a carrier has adopted there is the flexibility in the SCC architecture to fit in with the carrier’s existing model.
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