AppFabric Caching: What Now?

ScaleOut Software’s Windows Server AppFabric Caching Compatibility Library is a source-code compatible drop-in replacement for a seamless transition.

Two years ago we posted a blog on the performance and feature shortcomings of Microsoft’s Windows Server AppFabric (WSAF) Caching. Since then much has transpired. Microsoft announced earlier this year it will be ending support for Windows Server AppFabric 1.1 by April 2017. AppFabric Caching users now have to determine the best next step for migrating to an alternative distributed cache.

Recommended alternatives found lacking

With its "mobile first, cloud first" strategy, it appears that Microsoft is pushing customers to its Microsoft Azure cloud platform by recommending that "all Microsoft AppFabric customers using Cache to move to Microsoft Azure Redis Cache." However, for many customers it is not yet practical to move to Azure, and a fully supported, on-premise solution is required for their distributed cache. Microsoft’s recommendation that customers move to Redis is both controversial and misleading since the Redis open source community does not recommend running on Windows.

Further, Redis is an in-memory data structure store which works well on a single server but lacks many of the scalability and high-availability features of a mature, fully featured in-memory data grid, let alone real-time analytics and computing capabilities. Redis Cluster uses relatively immature technology in comparison to current, fully peer-to-peer in-memory data grids. For example, its master/slave design with eventual consistency does not provide the access guarantees and ease of use expected in transactional systems, and its reliance on client-side data sharding represents a step backwards in ease of use. This leaves customers with an uncertain and commercially unsupported future when migrating their on-premise, .NET compatible, distributed cache away from AppFabric Caching.

A better alternative

Luckily, ScaleOut Software has been loyally serving the .NET developer community with an industry-leading in-memory data grid for over a decade. ScaleOut’s architectural design philosophy focuses on delivering high performance with maximum ease-of-use. It employs a single, coherent architecture for integrating scalability and high availability; this architecture is transparently leveraged in all aspects of its in-memory data grid. We call this "scalable, highly available everything" — the platform goes beyond linear performance scaling for accessing grid objects and uses a common architecture for all features such as distributed locking, event processing, load-balancing, geographic replication, parallel computation and backup/restore.

The key benefits and advantages that set ScaleOut StateServer® apart from its industry peers are:

Coherent, peer-to-peer architecture

• ScaleOut StateServer uses a peer-to-peer architecture to avoid single points of failure and maximize ease of use. It avoids the need for a centralized configuration store (which is a single point of failure) by automatically replicating its configuration files on every cluster host. System administrators do not need to create and manage a configuration store; this is automatically handled by ScaleOut StateServer.
• ScaleOut StateServer’s peer-to-peer architecture allows servers to be easily added and removed from the membership. Servers automatically form a new membership and rebalance the workload as needed. The membership self-heals after a server failure, restores redundancy for high availability, and redistributes the workload as necessary.
• To meet the needs of transactional systems, ScaleOut StateServer implements a sequential consistency model for storing data within its in-memory data grid. Unlike distributed caches which employ eventual consistency when updating replicas, this guarantees that client applications always see the latest data, even after a server or NIC failure.

Ease-of-use

• ScaleOut StateServer’s acclaimed ease-of-use ensures that installation is extremely simple with minimum configuration steps. Unlike AppFabric Caching, it doesn’t require a highly qualified Windows system administrator to navigate the process of installing and configuring a distributed cache.
• ScaleOut StateServer’s centralized, GUI-based management console dramatically simplifies management and provides important capabilities, such as cluster-wide control, dynamic performance charting alerts, and a grid heat-map. Holistic visualization delivers at-a-glance monitoring, which is not possible with PowerShell and other text-based scripting approaches.
• ScaleOut Object Browser enables detailed introspection on the contents of the distributed cache, including access to values for object properties.

Extended functionality:

ScaleOut StateServer (and its product extensions) go far beyond AppFabric Caching’s basic capabilities and add important functionality, including:

• Distributed, property-based query using Microsoft LINQ
• Numerous API extensions, such as support for object dependencies and sliding timeouts
• Powerful object browser to directly browse data stored in the grid
• Scalable event handling
• Data-parallel computation, including the world’s first C# MapReduce
• Extensible support for building server-based data structures
• WAN-based data replication and synchronized, global data access
• Integrated support for public clouds, including Amazon AWS and Microsoft Azure

Furthermore, unlike Redis and some of the other open-source alternatives, ScaleOut StateServer is fully commercially supported by ScaleOut Software for use on Windows (as well as Linux for full portability).

Replacement and migration options

Customers have two paths to choose from when planning their migration off of AppFabric Caching to ScaleOut Software’s distributed cache: retain source-code compatibility for their existing legacy applications or migrate their applications to fully take advantage of native ScaleOut APIs.

Source-code compatible library

The ScaleOut Windows Server AppFabric (WSAF) Caching Compatibility Library is a source-code compatible, drop-in replacement for Microsoft AppFabric Caching APIs. This allows existing customer applications using AppFabric to preserve the legacy AppFabric Caching API semantics and switch to ScaleOut StateServer without making any code changes and use familiar PowerShell commands to manage the distributed cache. This library ships as part of ScaleOut StateServer release 5.4 and later, as described in the WSAF Caching Compatibility Library Reference.

Native ScaleOut APIs

Customers also can rewrite their applications to use ScaleOut StateServer’s native APIs, which allows applications to take full advantage of the extended functionality mentioned above. Using a hybrid approach, native ScaleOut StateServer APIs can be used alongside AppFabric APIs. We have developed a detailed technical AppFabric Caching migration guide to help developers through this process.

Using the WSAF Caching Compatibility Library

The WSAF Caching Compatibility Library is easy to integrate into applications that use AppFabric Caching’s APIs. Here is an outline of the required steps:

1. Add the compatibility library’s assembly (soss_wsaf_compat.dll) as a reference to the project. This assembly can be found in the ScaleOut StateServer installation folder (typically C:\Program Files\ScaleOut_Software\StateServer) in the Compat\WSAF_Caching folder.
2. Change the "using Microsoft.ApplicationServer.Caching;" statements in the source files to "using Soss.Compat.WSAF;".
3. Recompile the project to start using the WSAF Caching Compatibility Library.

For More Information

More information about all the AppFabric Caching replacement and migration resources available can be found at www.scaleoutsoftware.com/appfabric, including a valuable offer for former AppFabric Caching users. We hope that the power of our platform as both a replacement and an upgrade from Microsoft’s WSAF Caching has captured your interest. Regardless if you run on-premise or in the cloud, it may be the right next step for your application.