4 ms·

Yep... any enterprise is likely full of them: ldap: authentication microservice syslog: logging microservice smtp: messaging microservice smb/nfs:

Yep... any enterprise is likely full of them: ldap: authentication microservice syslog: logging microservice smtp: messaging microservice smb/nfs: file storage microservice They haven't been called that for the past 40 years, but that's what they are.

stingraycharles 8y ago
Back in the day it was called Service Oriented Architecture. Then CORBA happened and that became a curse word, and guess we will repeat this when HTTP/4.0 will feature RPC?
- ealexhudson 8y ago
  CORBA is a bit different: that's more about making remote code appear as if it were local, and having the network disappear. SOA isn't necessarily RPC: it could be message passing, for example. Async invocation like that in RPC is much tougher. I do think the distinction between "services" and "microservices" is a bit overblown. Clearly something like IMAP is not a microservice - it contains auth, storage, search and a few other pieces. Calling LDAP a microservice is potentially a stretch for similar reasons. But fundamentally, the concerns and architecture of both are extremely similar.
  - euske 8y ago
    > I do think the distinction between "services" and "microservices" is a bit overblown. I just realized that adding micro- or nano- or -oriented is a great way to create a buzzword in the current climate. Say, microsecurity, nanolearning, or anger-oriented user interface.
Thaxll 8y ago
Except that they don't really talk to each other and if they do it's using custom protocols. Also I wouldn't call those "micro".
- justinsaccount 8y ago
  They don't talk to each other? So you've never seen an smtp server store its spool on an nfs mount, authenticate against ldap, and log to a remote syslog server?
- sbov 8y ago
  A microservice doesn't have to be micro! They are oftentimes a single bounded context in domain driven design, which can be huge.
  - newaccoutnas 8y ago
    So, a service, then?
entity345 8y ago
Don't confuse applications and protocols with microservices. Microservices are services within an application.
- cestith 8y ago
  There's every chance your MX MTA authenticates people against LDAP, uses LDAP again to figure out where to forward the mail to another system for final account storage, then the MDA stores the message on a clustered file system or an object store, then tells the logging system to log the delivery. The LDAP systems for authentication and for where the user's mail lives might be separate instances. Then the MUA connects to an IMAP proxy which talks to LDAP to authenticate and to determine where the messages for this user are stored (again, possibly different LDAP instances), then connects to an IMAP backend that retrieves the data from a clustered file system or object store. The IMAP proxy, IMAP backend, and MDA are separate systems. The object store is, likewise, a separate system. Meanwhile some of your users are using a webmail client as their MUA. That talks to an outbound-only MTA and the IMAP proxy, but it may talk directly to LDAP for authentication rather than authenticating to the mail servers first. It can pull user preferences from LDAP. It pulls their contact book from LDAP. These might be three different LDAP instances. I has a calendar app in the same page in another tab, but that talks instead to a separate CalDav server. The folder pane which updates with the number of unread messages in each folder updates through a different backend process on a different web server from the listing of mail in your current folder, which is a separate web server from the one that just fetched the content of the highlighted message into your preview pane. Meanwhile. half of these systems actually forward through another MTA which makes no final delivery decision itself but scans for spam scoring. Those messages that make it through the filtering get forwarded to another service which only scans for malware. Then those messages which pass go to the system that forwards the mail for final delivery to the user or to the remote party's mx server. All of these systems need their timestamps correct, so they all talk to an NTP service running alone on a VM or container that does nothing else. All of these systems send their logs to a central logging cluster via a defined protocol. The logging servers do nothing else. Just because your mail server might run qmail, Courier, Amavis, SpamAssassin, procmail, and mutt on one box with local storage and local logging doesn't mean that's how mail is done at scale. It's pretty clear to me how if you think of "email" as the application that it is composed of microservices.

stingraycharles 8y ago

Back in the day it was called Service Oriented Architecture. Then CORBA happened and that became a curse word, and guess we will repeat this when HTTP/4.0 will feature RPC?

ealexhudson 8y ago
CORBA is a bit different: that's more about making remote code appear as if it were local, and having the network disappear. SOA isn't necessarily RPC: it could be message passing, for example. Async invocation like that in RPC is much tougher. I do think the distinction between "services" and "microservices" is a bit overblown. Clearly something like IMAP is not a microservice - it contains auth, storage, search and a few other pieces. Calling LDAP a microservice is potentially a stretch for similar reasons. But fundamentally, the concerns and architecture of both are extremely similar.
- euske 8y ago
  > I do think the distinction between "services" and "microservices" is a bit overblown. I just realized that adding micro- or nano- or -oriented is a great way to create a buzzword in the current climate. Say, microsecurity, nanolearning, or anger-oriented user interface.

Thaxll 8y ago

Except that they don't really talk to each other and if they do it's using custom protocols. Also I wouldn't call those "micro".

justinsaccount 8y ago
They don't talk to each other? So you've never seen an smtp server store its spool on an nfs mount, authenticate against ldap, and log to a remote syslog server?
sbov 8y ago
A microservice doesn't have to be micro! They are oftentimes a single bounded context in domain driven design, which can be huge.
- newaccoutnas 8y ago
  So, a service, then?

entity345 8y ago

Don't confuse applications and protocols with microservices. Microservices are services within an application.

cestith 8y ago
There's every chance your MX MTA authenticates people against LDAP, uses LDAP again to figure out where to forward the mail to another system for final account storage, then the MDA stores the message on a clustered file system or an object store, then tells the logging system to log the delivery. The LDAP systems for authentication and for where the user's mail lives might be separate instances. Then the MUA connects to an IMAP proxy which talks to LDAP to authenticate and to determine where the messages for this user are stored (again, possibly different LDAP instances), then connects to an IMAP backend that retrieves the data from a clustered file system or object store. The IMAP proxy, IMAP backend, and MDA are separate systems. The object store is, likewise, a separate system. Meanwhile some of your users are using a webmail client as their MUA. That talks to an outbound-only MTA and the IMAP proxy, but it may talk directly to LDAP for authentication rather than authenticating to the mail servers first. It can pull user preferences from LDAP. It pulls their contact book from LDAP. These might be three different LDAP instances. I has a calendar app in the same page in another tab, but that talks instead to a separate CalDav server. The folder pane which updates with the number of unread messages in each folder updates through a different backend process on a different web server from the listing of mail in your current folder, which is a separate web server from the one that just fetched the content of the highlighted message into your preview pane. Meanwhile. half of these systems actually forward through another MTA which makes no final delivery decision itself but scans for spam scoring. Those messages that make it through the filtering get forwarded to another service which only scans for malware. Then those messages which pass go to the system that forwards the mail for final delivery to the user or to the remote party's mx server. All of these systems need their timestamps correct, so they all talk to an NTP service running alone on a VM or container that does nothing else. All of these systems send their logs to a central logging cluster via a defined protocol. The logging servers do nothing else. Just because your mail server might run qmail, Courier, Amavis, SpamAssassin, procmail, and mutt on one box with local storage and local logging doesn't mean that's how mail is done at scale. It's pretty clear to me how if you think of "email" as the application that it is composed of microservices.