Azure Application Gateway

As explained in Microsoft Azure in Action

Azure Application Gateway is an Azure application delivery service that provides Layer 7 load balancing and routes web traffic to backend resources based on HTTP request properties such as host or path.

Azure Application Gateway distributes web traffic across backend virtual machines by inspecting the requested web address. It is the Layer 7 choice when routing should follow application URLs rather than only network protocols. section 3.3.4

Route traffic by path

Imagine llamadrama.com serving both images and video. Requests for /image can go to a VM managing images, while requests for /video go to a VM processing video. The gateway acts like a web-aware traffic director: it sends each request where that application function lives. section 3.3.4

Choose Application Gateway when:

• Traffic must be routed according to the requested web address. section 3.3.4
• Multiple virtual machines need to share inbound application traffic for better performance and availability. section 3.8
• Protocol-only balancing is not enough. Azure Load Balancer supports TCP and UDP traffic with higher performance and lower latency, but does not provide URL-based routing. section 3.3.4

Figure 3.24 Choose one of two load balancing options, if required.

Compare Azure Application Gateway and Azure Load Balancer when deciding how a VM or VM group should receive traffic. section 3.3.4

How Microsoft Azure in Action covers it

How deep it goes

Defines URL-based routing and contrasts protocol balancing, but defers creation and detailed configuration to later treatment.

Examples

Uses llamadrama.com paths to send image requests and video requests to different virtual machines.

What it assumes

Assumes familiarity with virtual machines, inbound traffic, and distributing workloads across multiple VMs.

What you can do after

Evaluate whether URL-aware routing or protocol-based balancing better fits a multi-VM application.

How it connects

Connects application delivery with virtual machines, VM scale sets, and Azure Load Balancer.

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Also explained in

• 

  liveBookmanning.com
  Azure SecurityAzure Application Gateway v2 is the second-generation deployment version of Azure Application Gateway that supports WAF policies.

Compare how 2 books explain Azure Application Gateway →

Related concepts

• Azure Web Application Firewallused by · Azure Web Application Firewall is an Azure-managed service that inspects web traffic and applies rules to protect HTTP applications from common exploits.
• WAF policyconfigured by · A WAF policy is a configuration resource that defines the rules, rule sets, and operating mode applied by a web application firewall.
• layer-7 load balancerkind of · A layer-7 load balancer distributes and routes application-layer requests using information such as protocols, paths, hostnames, and request contents.
• Azure Load Balanceralternative to · Azure Load Balancer is a managed Azure service that distributes network traffic across backend resources according to configured rules and health status.

This explainer was generated by Manning's knowledge graph from the text of Microsoft Azure in Action. The section links point to the parts of the book it draws on.