![]() ![]() A quick examination of the first window shows that the arrival of this second member was indeed detected. Just for fun, you can launch a few more “cluster members”. For some more fun: if your network allows multicast, “install” Coherence on some other machines in your network, and lauch a few servers on those machines as well. Double-click it again, and a new window pops up telling you that a new member was created and added to the existing cluster. Double-click it and a console window pops up with some logging that, upon examination, tells you that a cluster has been started with one member. ![]() The first script is called “cache-server.cmd”. And there is a “bin” directory with a few shell scripts. There a documentation directory with a User Guide and Javadoc. After unzipping it a few moments later, it turns out there is not even an installer. However, after listening to a number of excellent presentations on the subject, and after having downloaded and “installed” the software (you’ll find out why I put that between double quotes shortly), I can safely say that although nothing in the OTN quote above is untrue or even exaggerated, working with Oracle Coherence is ridiculously simple.ĭemystification occurs the moment the download begins: Oracle Coherence comes in the form of an 8Mb(!) zipfile. I don’t know what your impressions are after reading this, but my first thoughts were along the lines of: “Sounds like very complex cluster configuration and management, and probably it will be very difficult to program against”. Coherence includes network-level fault tolerance features and transparent soft re-start capability to enable servers to self-heal. When a new server is added, or when a failed server is restarted, it automatically joins the cluster and Coherence fails back services to it, transparently redistributing the cluster load. Coherence has no single points of failure it automatically and transparently fails over and redistributes its clustered data management services when a server becomes inoperative or is disconnected from the network. To describe what this technology is all about, lets start with a quote from OTN: Coherence provides replicated and distributed (partitioned) data management and caching services on top of a reliable, highly scalable peer-to-peer clustering protocol. The other is Oracle Coherence, known as Tangosol Coherence before Oracle acquired this technology recently. The first is CEP (Complex Event Processing), which I am sure will be covered in another post on this Blog in soon. Of all the new and exciting stuff I have seen at Oracle OpenWorld this year, two new technologies (at least to me) stand out. ![]()
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