## 5 Blueprint Template
### Virtual Architecture (VA) Section  
An element in a blueprint, _i.e._, a service offering, implementation artifact, or resource requirement, may have an interdependency or interconnection relationship with another blueprint element. The VA Section allows specifying the following relationships between elements within a blueprint or across blueprints, each with a Source and a Target element.  
* Vertical Link: This relationship indicates a \"direct\" deployment dependency between a blueprint element e and another blueprint element e', _i.e._, e needs to be deployed on e'. For instance, an implementation artifact directly depends on one or more resource requirements for its deployment. Vertical Links are transitive, which results in the so-called \"indirect\" deployment dependency, or the \"indirect\" vertical link.  
* Horizontal Link: This relationship indicates a \"direct\" functional dependency between a blueprint element e and another blueprint element e', _i.e._, e reuses the functionality of e'. For instance, a service offering reuses another service offering and hence, directly depends on its functionality. Horizontal Links are transitive, which results in the so-called \"indirect\" functional dependency, or the \"indirect\" horizontal link.
* Resource Link: We consider a virtual network resource as an IaaS service offering or IaaS resource requirement in a blueprint. A resource link is used to allocate blueprint elements to a virtual network resource. Hence, the target of a resource link is always a virtual network resource captured in either an IaaS service offering or an IaaS resource requirement.  
Figure 6 illustrates the joint VA graph of the _TaxiTilburg-Blueprint, Tele1-Blueprint, and AutoInGlueprint_ blueprints in the scenario from Section 2. This graph indicates:  
* The _TaxiOrdering-SBA_ offering requires the _TaxiMgt-SaaS_ offering of AutoInc and the _SMSDelivery-SaaS_ offering of Tele1.
* The _CMF.war_, _GoogleMapServices.war_, _TaxiCompany.war_, _TaxiTransmitter.war_ implementation artifacts require a JEE application server that includes a Servlet v2.5 container (_JEE/Servlet-Server-Req_).
* Other implementation artifacts of the _AutoInc-Blueprint_ blueprint require a BPEL Engine (_BPEL-Engine-Req_), which is supposed to be deployed on the _JEE/Servlet-Server-Req_.
* The required JEE application server (_JEE/Servlet-Server-Req_) is connected to the required Context-as-a-Service and to the outside by a network link 3 Gbit (_NetworkLink3 Gbit-Req_).  
In summary, the VA is an essential part of the Blueprint Template that specifies the to-be virtual architecture topology across blueprints. The VA graph in Figure 6 also indicates that the _TaxiMgt-SaaS_  
Figure 6: A sample Virtual Architecture (VA) graph.  
offering of the _AutoInc-Blueprint_ blueprint is \"unresolved\" as it still contains a number of resource requirements. In the further development phases of the blueprint, the resource requirements need to be resolved by searching and selecting appropriate blueprints from the blueprint repository. The _AutoInc-Blueprint_ blueprint becomes \"resolved\" if all the resource requirements can be fulfilled by the offerings of the newly retrieved blueprints.