Landscape Pattern 
A landscape pattern represents the relationship of a technical system to one or more product systems. When you classify technical systems by landscape pattern, you specify how they are maintained in the product system.
The product instances installed in a technical system can belong to several product systems, to which these technical systems must be assigned explicitly. In this way, you can use technical systems for several SAP applications in parallel. You can also restrict maintenance transactions to one selected product version, without creating additional maintenance requirements due to dependencies on other product versions.
Hub
Technical systems with the landscape pattern Hub are used by more than one product system, and thus by more than one SAP application. You can perform separate maintenance transactions for each of these product systems, independently. The Hub technical system is part of each of these maintenance transactions.
When determining a consistent target status for the Hub technical system, as few software components as possible are changed. This avoids additional dependencies between the technical system and the product systems that use it.
Example
In this example, the product system <ABC> has the active product version SAP NetWeaver 7.00. The product instance SAP NW - EP Core is installed in the associated technical system, and is used in parallel by installed product instances of two other product systems: SAP XSS and ERP Business Packages (product system <RST>), and SAP SRM Content (product system <UVW>).
So you assign the landscape pattern Hub to this technical system.
Updates or maintenance of this technical system depend on the active product version (SAP NetWeaver 7.00) of the product system. The Maintenance Optimizer calculates a consistent target status for the affected software component in the technical system.
In the other technical systems, update or maintenance also depend on the active product version (SAP ERP 6.0 EHP4, SAP SRM 7.0 EHP1) of the product system. So you can perform a maintenance transaction for each product system independently.
Sidecar
Technical systems that you have assigned to the Sidecar landscape pattern are used by exactly one product system.
The target status of a Sidecar technical system in a maintenance transaction, is determined by the active product version of the product system. An up-to-date and synchronized combination of the release statuses of the software component versions used, is determined, as the target status.
Example
In this example, product system <XYZ> has the active product version SAP ERP 6.0, and the relevant product instances are distributed to two separate technical systems:
AS ABAP and the ERP product instance ECC server are installed on the first technical system.
The ERP product instances ERP Business Packages SAP XSS and SAP FSCM Biller Direct, which use the product instance SAP NW EP Core locally, are installed in the second technical system, as well as AS JAVA. In update or maintenance, only the dependence of SAP NW EP Core on the active product version (SAP ERP 6.0) is relevant.
So you assign the landscape pattern Sidecar to the second technical system.
Updates or maintenance of this technical system depend on the active product version of the product system. The Maintenance Optimizer determines a synchronized target status for the various software components, depending on this.
