In your entire software development, sooner or later you will got a few project with very low budget, where you can't use commercial software because the budget is low and in the long run company also want some profit completing the project. From the begging of the year i have done a few pre-sale for such projects and decided to write down a list of all open source alternatives against commercial product. One thing i have to clear that, i have no religious view over open sources software or vica verse. There a plenty of reasons to use most of the commercial product but most of all time we have to cut our coat according to our cloths.
Most of all vendor like Oracle and IBM have their finest product in BPM, such as Oracle BPM Server, IBM Business process manager. Also you can find a few very good open source product such as JBPM from Jboss and Bonitasoft. But their are another very good open source BPM engine you can try, it's Activity. Spring based (state machine) light weight engine that you can use in standalone or in web application. We develop our mobile number portability project based on this BPM engine and it's works more than a year. Here you can find a few screen shot to check how it cloud looks like.
I am a real fun of Oracle OSB, completed more than two project successfully on this platform. It's has all the functionality you need for enterprise service bus or integration with another system. If you are looking for open source ESB, the first option should be glassfish ESB and mule. WSo2 is also a very good candidate for choose.
3) Business Rules:
Best business rules software i have ever used was IBM ILOG Jrules. It's consistence, reliable and synchronization capabilities with user code base. There are not so much open source alternatives in this sector, Drools from jboss is one of the good candidate. Certainly Drools contains a lot of bugs with it's functionality but you should make a try on this.
4) Messenging server: IBM MQ series is one of the best messenging server ever and most of banking sector and telecommunication company using this product with great successfully. This is unbreakable software with all the messenging functionality such as transition queue. Most of the company already have the unlimited licenses for using this software, however unfortunately if you need some open source version, you have a very wide choose. Active MQ, Apollo or RabbitMQ can be you choose. Here you can found the complete list of the mq servers. When i am looking for any open source MQ server, i have the following requisites to this product:
- It should be fast
- it's have to persist messages in disk
- it should be work on cluster with failover capabilities
5) LDAP: Off course Microsoft Active directory is one of the best candidate in LDAP, Microsoft AD has their own LDAP implement ion. If you have to use NTLM or kerberos, first choose should be Microsoft AD. As a opensource openldap is best option.
6) Application server:
Most of all time i am working with Oracle Web logic server and IBM WAS. Be honest they are the best in application server. In this sector there are a lot of candidate you will find in open source. But whenever i have to choose open source version, i always preferred Glassfish application server, because it's reliable. Off course you have a much more option like jboss, tomcat, jetty e.t.c.
7) Database: If you have unlimited licenses to Oracle, never thought about any other vendor or product for DB. Oracle DB is reliable and consistency for a long time. Whenever you have to choose for open source RDBMS version, you should try postgres and mySQL.
8) In memory Datagrid: Oracle coherence is the best commercial software for implementing In memory Datagrid. Company hazelcast also have open source version of in memory data grid. With hazelcast you can easily use distributed queue, map and list and much more. From the beginning of Hazelcast, i used it for hibernate l2 cache.
9) Distributive cache: If you are fun of Infinispan for some reason, you should make a try to ehcahe or jboss cache. With jgroups configuration ehcache can be use as distributive cache. Ehcache capable to configure heap with many other ways and contains a lot of algorithms such as LRU.
10) web server and load balancer: Here we have also a few options against commercial Alteon load balancer. For security reasons most of all banks and telecommuncation company using Alteon. If this is not for your reason, you must try nginx and varnish. Nginx can use not only web server but also load balancer.
Above all information is my personal opinion and from my personal expertise. May be it can be differs from many of us. If there are more options please don't hesitated to add in comment.