web server and web app server

[woo]

Hello,

Please help to understand how web server, web app server and apache tomcat is related? I have read mid-tier sas documentation but it gets bit confusing. I know web app server is where we have multiple server instances (like SASServer1_1, 2_1 and so on). do we really need apache tomcat (Linux based) for webserver and does it (apache tomcat) still require to start/restart separately just in case if needed (separate from web server start/restart  .../lev1/Web/WebServer/bin/httpdctl)? what is .../sashome/SASWebApplicationServer/9.4/tomcat/bin/catalina.sh" stand for? what it does? does sas web app server still require any other web app platform (like IBM webspear or oracle weblogic) to run? Thank you!!!

[dpage · Accepted solution]

The web server acts as a load balancer and reverse proxy for the web application servers - it is actually optional in some configurations, but you will typically see it. 

You can read more details about it here. 

https://go.documentation.sas.com/?docsetId=bimtag&docsetTarget=n0axzi2o0wubxan1cgaovjqqjfho.htm&docs...

the web application server runs the various java based web applications SAS provides. You do not need to provide tomcat, and the catalina.sh that's in your SAS Home path is not something you directly invoke.

https://go.documentation.sas.com/?docsetId=bimtag&docsetTarget=n0kn00ddbhus6zn18h6t4b7vn7ed.htm&docs...

covers how it's operated - if you wanted to stop/start servers individually. It's much more common to use the sas.servers script or appsrvconfig.cmd to start all of the servers (and their pre-requisites) at the same time. 

the sas web app servers are a replacement for things like JBoss/WebSphere/Weblogic. See the Changes to the middle tier section here:

https://go.documentation.sas.com/?docsetId=whatsdiff&docsetTarget=n1roydrale7528n14alj43gi257f.htm&d...

[woo]

Thanks. appreciate your response. so there is no relation/tie that sas has with Linux OS based tomcat apache server at all? it has nothing to do sas web apps?

[dpage]

we do not use the system installed tomcat, if that's what you're asking.

The sas web application server is based on tomcat - https://go.documentation.sas.com/?docsetId=whatsnew&docsetTarget=p05re4h7drh86rn1xp8x6379otlj.htm&do...

and by default, we use port 8080 for SASServer1_1 which will be a conflict. 

[woo]

thank you so much for explaining.