Citrix Web Interface - Client Communications
The diagram below shows the client communications when accessing Citrix XenApp via the Citrix Web Interface:
1. The Web server reads users’ credentials and forwards the information to the Citrix XML Service on servers in the server farms. The designated server configured with Web interface console acts as a broker between the Web server and the other servers in the farm.
2. The Citrix XML Service on the designated server retrieves from the servers a list of applications that users can access. These applications comprise the user’s application set. The Citrix XML Service retrieves the application set from the Independent Management Architecture (IMA) system.
3. The Citrix XML Service then returns the user’s application set information to the Web Interface running on the server.
4. The user clicks an application icon in the HTML page.
5. The Citrix XML Service is contacted to locate the server in the farm that is the least busy. The XML Service identifies the least busy server and returns the address of this server to the Web Interface.
6. The Web Interface generates a customized .ica file and sends it to the Web browser.
7. The Web browser receives the file and passes it to the client device. The client receives the file and initiates a client session with a server according to the file’s connection information.
8. The client receives the file and initiates a client session with a server according to the file’s connection information.
Citrix License Server Communication
The diagram below shows the common components of Citrix Presentation Server 4 licensing:
The IMA service starts, e.g. as the server reboots.
The IMA service reads its configuration from the IMA data store.
1. This configuration information includes the name of a Citrix license server and a TCP port number that should be used. This is port 27000.
2. The Presentation server contacts the license server on the port specified in the data store Port 27000.
3. On the license server, the license manager daemon listens for initial client connection requests on port 27001 and responds by redirecting the client to the Citrix vendor daemon running on the same server.
4. The Citrix vender daemon listens by default on the port (this process tracks and issues server and connection licences).
5. The Presentation Server then maintains a persistent connection to the Citrix vendor daemon on the license server which is used to check licences in and out.
Normal communication takes place every time a user launches a session, logs out, reconnects, or disconnects. The Presentation Server sends a message to the license server, via the previously established persistent connection, so that the license server can track how many licenses are available. In essence, the Presentation Server “checks out” a license on behalf of a user. Heartbeat communication takes place if no license activity happens for 120 seconds. The two servers exchange heartbeat information so that they both know that the other is still there.
Citrix Datastore Communication
The diagram below shows the common components of Citrix Presentation Server 4 Datastore:
When you start a server, it must initialize the IMA Service and also register with the data collector for the zone in which it resides.
1. The IMA Service establishes a connection to the farm’s data store and then downloads the information it needs to initialize. It also ensures that the data contained in its local host cache is current.
2. After the IMA Service is initialized, the member server registers with the data collector for the zone.
3. Next, the data collector relays all of the updated information written by the member servers in the zone to all other data collectors in the farm to keep them synchronized with each other. (this is good practice to have this, but as “COMPANY A” do not have this open it does not cause issues, because each collector within the zone can contact the Datastore)
The diagram below shows the client communications when accessing Citrix XenApp via the Citrix Web Interface:
Client device utilize a Web browser to authenticate to the Web Interface.
1. The Web server reads users’ credentials and forwards the information to the Citrix XML Service on servers in the server farms. The designated server configured with Web interface console acts as a broker between the Web server and the other servers in the farm.
2. The Citrix XML Service on the designated server retrieves from the servers a list of applications that users can access. These applications comprise the user’s application set. The Citrix XML Service retrieves the application set from the Independent Management Architecture (IMA) system.
3. The Citrix XML Service then returns the user’s application set information to the Web Interface running on the server.
4. The user clicks an application icon in the HTML page.
5. The Citrix XML Service is contacted to locate the server in the farm that is the least busy. The XML Service identifies the least busy server and returns the address of this server to the Web Interface.
6. The Web Interface generates a customized .ica file and sends it to the Web browser.
7. The Web browser receives the file and passes it to the client device. The client receives the file and initiates a client session with a server according to the file’s connection information.
8. The client receives the file and initiates a client session with a server according to the file’s connection information.
Citrix License Server Communication
The diagram below shows the common components of Citrix Presentation Server 4 licensing:
The IMA service starts, e.g. as the server reboots.
The IMA service reads its configuration from the IMA data store.
1. This configuration information includes the name of a Citrix license server and a TCP port number that should be used. This is port 27000.
2. The Presentation server contacts the license server on the port specified in the data store Port 27000.
3. On the license server, the license manager daemon listens for initial client connection requests on port 27001 and responds by redirecting the client to the Citrix vendor daemon running on the same server.
4. The Citrix vender daemon listens by default on the port (this process tracks and issues server and connection licences).
5. The Presentation Server then maintains a persistent connection to the Citrix vendor daemon on the license server which is used to check licences in and out.
Normal communication takes place every time a user launches a session, logs out, reconnects, or disconnects. The Presentation Server sends a message to the license server, via the previously established persistent connection, so that the license server can track how many licenses are available. In essence, the Presentation Server “checks out” a license on behalf of a user. Heartbeat communication takes place if no license activity happens for 120 seconds. The two servers exchange heartbeat information so that they both know that the other is still there.
Citrix Datastore Communication
The diagram below shows the common components of Citrix Presentation Server 4 Datastore:
When you start a server, it must initialize the IMA Service and also register with the data collector for the zone in which it resides.
1. The IMA Service establishes a connection to the farm’s data store and then downloads the information it needs to initialize. It also ensures that the data contained in its local host cache is current.
2. After the IMA Service is initialized, the member server registers with the data collector for the zone.
3. Next, the data collector relays all of the updated information written by the member servers in the zone to all other data collectors in the farm to keep them synchronized with each other. (this is good practice to have this, but as “COMPANY A” do not have this open it does not cause issues, because each collector within the zone can contact the Datastore)
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