Maybe you're old school and call them load balancers. Or perhaps you're slightly more modern and say application...
delivery controllers (ADC). Or are you thoroughly modern and use the term application delivery platform (ADP)? Whatever you call them, the devices and software-as-a-service offerings that manage the flow of traffic between end users and enterprise systems are more important than ever. Load balancers, ADCs, ADPs -- whatever the terminology, the specific tool for aiding application delivery can vary considerably; organizations should make sure to match the platform they select to their own specific needs.
Today's ADP: Form factor matters … sometimes
Form factor is an important consideration. When the ADP was born (back in the load-balancing days), IT service delivery environments were dominated by on-premises resources, bolstered by co-located -- and some dedicated -- hosted systems. A box you could stick in front of a stack of other boxes (the Web servers, typically) was a great solution. In today's hybrid service delivery environment, which is nearly completely virtualized and where a substantial portion of the enterprise workload is shifted to a changing mix of cloud-based services, the same is not true. So, first and foremost, unlike the old load balancers, a new ADP should have a virtual form factor for both in-house -- whether on-premises or colocated -- and infrastructure as a service (IaaS) deployments (particularly for the IaaS platforms the enterprise either uses or plans to use.). Ideally, the virtual implementation will permit the ADP to follow a workload if the workload gets moved.
Not everything you knew about load balancers is outdated. For instance, a physical appliance can still be important -- especially for those infrastructures with farms of dedicated (not virtual) Web servers on the front end. The same is true if there are compliance requirements that require a physical appliance with specific characteristics, such as FIPS 140-2 tamper-proof crypto modules. Ideally, a physical appliance will itself support in-chassis virtualization. This will allow it to share its resources across multiple independent virtual ADP instances that may be tailored to greater security, simplified management per application and multi-tenant service delivery.
Of course, if the ADP is a delivered as a service, considerations of form factor become moot; services are provided and implementation is abstracted away.
Scale is a second important consideration. As the rise of microservices forces IT to shift to a more service-oriented approach, ADPs have to manage more traffic for far more entities. At the same time, they have to deal with increasing amounts of east/west traffic among the services -- a flow of data sometimes more frequent and more voluminous than end-user traffic. To address this growth in traffic, an ADP should offer an approach that scales, either vertically (bigger boxes, either physical or virtual) or horizontally (more boxes serving narrower slices of the pie). Or, ideally, both. Where ADP products scale horizontally, management tools must obscure the complexity through simple, single-pane-of-glass interfaces.
Set of services
Third, the set of services beyond simple load balancing is crucially important. IT service use patterns have shifted dramatically. Employees work from anywhere, on any kind of device and at any time of day. Increasingly, all communications between end users and services, or simply among services, is being encrypted.
As a consequence, organizations should favor ADPs engineered with multiple layers of functionality -- such as mobile-specific optimizations -- to support those work-anywhere sessions. Encryption-offload features can both speed up response times and reduce the number of servers needed to run the applications.
Last but not least
Finally, any ADP should have a robust API for integration into data center automation initiatives and manipulation by cloud orchestration and management platforms. Deep and comprehensive automation is no longer optional: Any ADP should be ready to do its part.
Whether an ADP is physical or virtual, in-house or as a service, its role is only becoming more important. When something absolutely positively has to be there in 100 milliseconds, you need ADP -- and that means IT must consider emerging needs and options to determine which ADP it needs.
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