Ably vs Google Cloud Pub/Sub

As we have datacenters globally, we can ensure that your users always experience the lowest possible latency by connecting to the closest datacenter, and have complete availability by connecting to alternative healthy datacenters when necessary.

Google Cloud Pub/Sub can rely on Google’s existing datacenters across the globe in the Americas, Asia and Europe.

Our latency based routing ensures that users anywhere in the world connect through one of our 385 edge acceleration PoPs to one of our 7 Ably datacenters.

When a client connects to Google Cloud Pub/Sub the router will connect to the datacenter with the shortest network distance.

Encoding messages in binary format is faster. It reduces bandwidth to send and receive messages, and streamlines the processing time for clients and servers when encoding and decoding messages.

Google Cloud Pub/Sub allow for binary encoding only over gRPC and protobuff.

The Ably platform is designed with no single point of failure and to be self-healing. All our customers benefit from their apps running on all of our datacenters providing resilience, reliability and low latencies globally.

Google Cloud Pub/Sub use routing constraints to move traffic away from datacenters that are not functioning as expected.

Ably's servers are located in 7 datacenters covering 4 continents with each datacenter designed to operate as part of the global cluster when available, but operate autonomously when necessary.

Google Cloud Pub/Sub operates servers located in 56 datacenters across 4 continents which can operate as part of a global cluster or autonomously when necessary.

Ably stores every message in at least two datacenters and separate geographical regions. This ensures that an outage in any datacenter or region cannot result in data loss.

Ably provides guaranteed message delivery and continuity across disconnections. Publishers only receive an ACK when data is persisted in two locations, and subscribers never lose data during brief disconnections as we maintain connection state for each client on our servers.

With Google Cloud Pub/Sub, a published message is stored in the Google Cloud service until the client reconnects, and confirms it has received the message with an ACK.

Ably offers varying levels of uptime guarantees depending on your needs. For all of our enterprise customers we provide a 99.999% uptime SLA.

Google Cloud Pub/Sub only offer a SLA up to 99.95% uptime.

Data published into Ably's realtime system can be moved into traditional message queues for realtime or batch processing.

Google Cloud Pub/Sub also supports this feature.

Ably's Webhooks provide a means to get messages, channel lifecycle and present events pushed to your servers over HTTP.

Both Ably and Google Cloud Pub/Sub support the use of Webhooks.

Ably can trigger serverless functions on any third party platforms such as Amazon Lambda, Microsoft Azure or Google Function.

Google Cloud Pub/Sub only offer server-less functions on their own Google function thus limiting the choices available to you.

Presence allows you to subscribe to events when users or devices enter or leave channels. This is a useful feature for collaborative apps, games and chat rooms.

Google Cloud Pub/Sub does not support Presence, you can only check who is subscribed, not their status in an automated fashion.

Ably's message history feature provides a means for clients or servers to retrieve messages that were previously published on a channel.

Google Cloud Pub/Sub only allows you to obtain your subscription history if you’ve not yet ACK’d. Once you have retrieved your messages, you can no longer retrieve them again. Snapshots are a method that Google Cloud Pub/Sub use to remember certain parts of communication however.

Stream your realtime data published within the Ably platform directly to another streaming or queueing service such as Amazon Kinesis, Apache Storm or Kafka.

Ably ensures that messages are delivered to persistently connected subscribers in the order they were published on each channel.

Google Cloud Pub/Sub does not guarantee first order and instead publishes messages as fast as possible. This could cause issues with messages being received by subscribers in the wrong order; an issue that would not occur using Ably.

Ably supports Push notifications, whilst Google Pub/Sub does not innately support it.

Ably supports custom domains for our Enterprise customers allowing them to connect to Ably using a CNAME such as "realtime.your-company.com".

Google Cloud Pub/Sub does not support the use of CNAME.

Ably offer a considerable range of client libraries for every popular platform.

Google Cloud Pub/Sub has few libraries for client platforms, mainly focusing on server platforms.

Ably provides continuity for clients that become disconnected for reasons such as going through a tunnel or changing networks. Ably stores the connection state for each client on its servers so that clients that reconnect within two minutes can resume their connection and receive all messages published whilst they were disconnected.

WebSockets are widely regarded as the most efficient HTTP compatible transport for full duplex realtime communication between devices.

Google Cloud relies primarily on gRPC.

Whilst most modern devices support WebSockets, there are situations where the device or the network environment requires use of HTTP transports.

Google Cloud Pub/Sub has HTTP as a secondary option to gRPC.

Ably and Google Cloud Pub/Sub offer TLS connections ensuring that all data in transit is encrypted.

Token based authentication ensures your private key is never shared and instead a short-lived token is used to authenticate.

Ably allows configurable policies and an identity to be embedded in a token ensuring you have complete control over what actions your users can perform such as limiting which channels they can subscribe or publish to.

Google Cloud Pub/Sub only support the verification of messages from their servers using token authentication.

Ably and Amazon IoT provides support for private API keys with configurable permissions including restrictions on channels or operations.

Google Cloud Pub/Sub does not support configurable private key permissions.

Ably provides channel rules providing you with the flexibility to maintain control of your channels, such as requiring SSL/TLS or only identified authenticated clients on a channel.

Google Cloud Pub/Sub does not support configurable channel permissions.

Ably's AES encryption allows messages to be encrypted using the provided private key before they are published to Ably. As a result, messages are practically impossible to intercept and view for anyone including Ably. For very sensitive data, this ensures you can safely use us knowing your payloads are always secure and opaque.

Google Cloud Pub/Sub does not provide encrypted message payloads in their client libraries.