Paas, CloudFoundry and UI
User Interfaces and portals for Web applications have traditionally been deployed to dedicated virtual machines and are bound to it. When such applications need to be migrated, it involves manual intervention and planning. But both applications and services can both take benefits of CloudFoundry and PaaS. They are not restricted to the same physical machine that they were once deployed on. With these software, the applications and services can be rolled from one host to another seamlessly without any loss of functionality. They don't require any updates either to code or configuration when they are rolled between hosts.
User Interface is no exception. If APIs and services can avail the advantages of PaaS which include such things as automated code deployments from source control using say Jenkins, continuous monitoring of applications and services, consistent maintenance across applications and services, availability of multiple buildpacks and server software to host the applications. We will go through these benefits in detail shortly but let us take a look at the hosting requirements between API and UI in PaaS.
API software usually exposes an http/https endpoint and port for connectivity. While it may involve authentication, encryption and use of api-keys, all of these are done over basic authentication scheme or OAuth, they are contained to api implementations and external service consolidators such as a gateway. A user interface on the other hand may have to integrate with an identity provider and authentication mechanism such as SAML or OAuth external and probably central to an organization and not necessarily within the control of the applications and services framework. Fortunately these are facilitated with a route from the PaaS. The application merely has to handle the redirects from the said authentication mechanisms and the redirects are to specific name:port that can be ported between PaaS hosts as routes. The external ip address of the host and port can be retrieved in code as CF_INSTANCE_ADDR and CF_INSTANCE_PORT
Most of the UI code is generally written as static drop in /var/www folder or as a server side software such as node.js or django. In either case, the provisioning of UI could be attempted on CloudFoundry and PaaS by deploying the code and setting the environment variables such as HOME and WEBDIR
#codingexercise
Yesterday we discussed Hamiltonian cycles from complete graphs.
Permutations of a string:
Void Permute (String a, StringBuilder b, bool[] used, List<string> edges)
{
If ( b.Length == a.Length) { if ( edges.Any(x => b.contains(x)) == false) print b.ToString(); return;}
For (int I = 0; I < a.Length ; i++)
{
If (used[i]) continue;
used[i] = true;
B += A[i];
Permute(a, b, used, edges);
B [B.Length – 1] = ‘/0’;
used[i] = false;
}
}
Not the forbidden edges can actually be enumerated in different combinations and excluded from the permutations before a permutation reaches full length.
User Interfaces and portals for Web applications have traditionally been deployed to dedicated virtual machines and are bound to it. When such applications need to be migrated, it involves manual intervention and planning. But both applications and services can both take benefits of CloudFoundry and PaaS. They are not restricted to the same physical machine that they were once deployed on. With these software, the applications and services can be rolled from one host to another seamlessly without any loss of functionality. They don't require any updates either to code or configuration when they are rolled between hosts.
User Interface is no exception. If APIs and services can avail the advantages of PaaS which include such things as automated code deployments from source control using say Jenkins, continuous monitoring of applications and services, consistent maintenance across applications and services, availability of multiple buildpacks and server software to host the applications. We will go through these benefits in detail shortly but let us take a look at the hosting requirements between API and UI in PaaS.
API software usually exposes an http/https endpoint and port for connectivity. While it may involve authentication, encryption and use of api-keys, all of these are done over basic authentication scheme or OAuth, they are contained to api implementations and external service consolidators such as a gateway. A user interface on the other hand may have to integrate with an identity provider and authentication mechanism such as SAML or OAuth external and probably central to an organization and not necessarily within the control of the applications and services framework. Fortunately these are facilitated with a route from the PaaS. The application merely has to handle the redirects from the said authentication mechanisms and the redirects are to specific name:port that can be ported between PaaS hosts as routes. The external ip address of the host and port can be retrieved in code as CF_INSTANCE_ADDR and CF_INSTANCE_PORT
Most of the UI code is generally written as static drop in /var/www folder or as a server side software such as node.js or django. In either case, the provisioning of UI could be attempted on CloudFoundry and PaaS by deploying the code and setting the environment variables such as HOME and WEBDIR
#codingexercise
Yesterday we discussed Hamiltonian cycles from complete graphs.
Permutations of a string:
Void Permute (String a, StringBuilder b, bool[] used, List<string> edges)
{
If ( b.Length == a.Length) { if ( edges.Any(x => b.contains(x)) == false) print b.ToString(); return;}
For (int I = 0; I < a.Length ; i++)
{
If (used[i]) continue;
used[i] = true;
B += A[i];
Permute(a, b, used, edges);
B [B.Length – 1] = ‘/0’;
used[i] = false;
}
}
Not the forbidden edges can actually be enumerated in different combinations and excluded from the permutations before a permutation reaches full length.
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