Kev’s Blog – Kev's Development Toolbox

April 5, 2020April 5, 2020

The Hobbit for the ZX Spectrum: a text adventure with interactive NPCs from 1982

After having a Lord of the Rings and The Hobbit movie marathon this weekend, I fired up a ZX Spectrum emulator and relived playing the text adventure game The Hobbit. I shared some screenshots in this thread on Twitter here:

We're having a Lord of the Rings film marathon so loaded up The Hobbit on the speccy emulator #zxspectrum pic.twitter.com/MXmKQBqUP4
— Kevin Hooke (@kevinhooke) April 5, 2020

The Hobbit was released in 1982 for the ZX Spectrum. For it’s time, it has some interesting features, like NPCs that wandered around, and language parsing of statements allowing you to interact with the NPCs, like ‘say to Elrond “read map”‘.

Given the unusual (for the time) ability to interact with the NPCs, there even exists a ZX Spectrum emulator specifically to play The Hobbit, which also shows the state of the interactive characters and objects in the game as you play. This is well worth taking a look at to get an insight into how the game works – quite an achievement for an 8 bit game in only 48k: http://members.aon.at/~ehesch1/wl/wl.htm

March 30, 2020March 30, 2020

node.js, node-oracledb and Oracle Instant Client

To access an Oracle DB from an AWS Lambda function developed with node.js, you need to package you Lambda with shared libraries from Oracle’s Instant Client. The install instructions are here ( http://oracle.github.io/node-oracledb/INSTALL.html#quickstart ) but the only part that is really needed is the download location (since there’s no specific instructions for bundling the libs with an AWS Lambda): https://www.oracle.com/database/technologies/instant-client/linux-x86-64-downloads.html

Not all the Oracle Instant Client files are needed. From this older npm module to automate the packaging of the required libraries, I used this same list of required libraries:

libclntshcore.so.19.1
libclntsh.so.19.1
libmql1.so
libipc1.so
libnnz19.so
libons.so (not packaged in current Instant Client)
libociicus.so
libaio.so (from separate download - see next step)

libaio – if you’re on a Linux platform you can ‘apt-get install libaio’ or similar, but building my Lambda on a Mac I had to manually download the package and extract just the .so file from here (download the Arch Linux x64 package): https://pkgs.org/download/libaio

Put these in a /lib dir and zip up the folder and files. Use this to create a Lambda Layer.

For the Lambda itself install the node.js module for the api:

npm install –save node-oracledb

For examples in api usage, see the examples here: https://github.com/oracle/node-oracledb/tree/master/examples

March 29, 2020March 29, 2020

Installing Oracle Instant Client and Tools in an AWS EC2

I’m using the AWS Amazon Linux 2 AMI on my EC2. To download the Oracle Instant Client get the download urls for the instant client and instant client tools from: https://www.oracle.com/database/technologies/instant-client/linux-x86-64-downloads.html

Download using curl and install with rpm:

curl instant-client-url-from-page-above --output instant-client.rpm
rpm -i instant-client.rpm
curl instant-client-tools-from-page-above --output instant-client-tools.rpm
rpm -i instant-client-tools.rpm

To connect using sql-plus:

sqlplus 'admin@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=your-instance-endpoint.rds.amazonaws.com)(PORT=1521))(CONNECT_DATA=(SID=your-db-name)))'

Enter password when prompted.